给定两个整数’n’和’m’,求[n,m]范围内的所有步进数。有个号码叫 步进数 如果所有相邻数字的绝对差值为1。321是步进数,而421不是。
例如:
Input : n = 0, m = 21Output : 0 1 2 3 4 5 6 7 8 9 10 12 21Input : n = 10, m = 15Output : 10, 12
方法1:暴力手段 在该方法中,使用蛮力方法迭代从n到m的所有整数,并检查其是否为步进数。
C++
// A C++ program to find all the Stepping Number in [n, m] #include<bits/stdc++.h> using namespace std; // This function checks if an integer n is a Stepping Number bool isStepNum( int n) { // Initialize prevDigit with -1 int prevDigit = -1; // Iterate through all digits of n and compare difference // between value of previous and current digits while (n) { // Get Current digit int curDigit = n % 10; // Single digit is consider as a // Stepping Number if (prevDigit == -1) prevDigit = curDigit; else { // Check if absolute difference between // prev digit and current digit is 1 if ( abs (prevDigit - curDigit) != 1) return false ; } prevDigit = curDigit; n /= 10; } return true ; } // A brute force approach based function to find all // stepping numbers. void displaySteppingNumbers( int n, int m) { // Iterate through all the numbers from [N,M] // and check if it’s a stepping number. for ( int i=n; i<=m; i++) if (isStepNum(i)) cout << i << " " ; } // Driver program to test above function int main() { int n = 0, m = 21; // Display Stepping Numbers in // the range [n, m] displaySteppingNumbers(n, m); return 0; } |
JAVA
// A Java program to find all the Stepping Number in [n, m] class Main { // This Method checks if an integer n // is a Stepping Number public static boolean isStepNum( int n) { // Initialize prevDigit with -1 int prevDigit = - 1 ; // Iterate through all digits of n and compare // difference between value of previous and // current digits while (n > 0 ) { // Get Current digit int curDigit = n % 10 ; // Single digit is consider as a // Stepping Number if (prevDigit != - 1 ) { // Check if absolute difference between // prev digit and current digit is 1 if (Math.abs(curDigit-prevDigit) != 1 ) return false ; } n /= 10 ; prevDigit = curDigit; } return true ; } // A brute force approach based function to find all // stepping numbers. public static void displaySteppingNumbers( int n, int m) { // Iterate through all the numbers from [N,M] // and check if it is a stepping number. for ( int i = n; i <= m; i++) if (isStepNum(i)) System.out.print(i+ " " ); } // Driver code public static void main(String args[]) { int n = 0 , m = 21 ; // Display Stepping Numbers in the range [n,m] displaySteppingNumbers(n,m); } } |
Python3
# A Python3 program to find all the Stepping Number in [n, m] # This function checks if an integer n is a Stepping Number def isStepNum(n): # Initialize prevDigit with -1 prevDigit = - 1 # Iterate through all digits of n and compare difference # between value of previous and current digits while (n): # Get Current digit curDigit = n % 10 # Single digit is consider as a # Stepping Number if (prevDigit = = - 1 ): prevDigit = curDigit else : # Check if absolute difference between # prev digit and current digit is 1 if ( abs (prevDigit - curDigit) ! = 1 ): return False prevDigit = curDigit n / / = 10 return True # A brute force approach based function to find all # stepping numbers. def displaySteppingNumbers(n, m): # Iterate through all the numbers from [N,M] # and check if it’s a stepping number. for i in range (n, m + 1 ): if (isStepNum(i)): print (i, end = " " ) # Driver code if __name__ = = '__main__' : n, m = 0 , 21 # Display Stepping Numbers in # the range [n, m] displaySteppingNumbers(n, m) # This code is contributed by mohit kumar 29 |
C#
// A C# program to find all // the Stepping Number in [n, m] using System; class GFG { // This Method checks if an // integer n is a Stepping Number public static bool isStepNum( int n) { // Initialize prevDigit with -1 int prevDigit = -1; // Iterate through all digits // of n and compare difference // between value of previous // and current digits while (n > 0) { // Get Current digit int curDigit = n % 10; // Single digit is considered // as a Stepping Number if (prevDigit != -1) { // Check if absolute difference // between prev digit and current // digit is 1 if (Math.Abs(curDigit - prevDigit) != 1) return false ; } n /= 10; prevDigit = curDigit; } return true ; } // A brute force approach based // function to find all stepping numbers. public static void displaySteppingNumbers( int n, int m) { // Iterate through all the numbers // from [N,M] and check if it is // a stepping number. for ( int i = n; i <= m; i++) if (isStepNum(i)) Console.Write(i+ " " ); } // Driver code public static void Main() { int n = 0, m = 21; // Display Stepping Numbers // in the range [n,m] displaySteppingNumbers(n, m); } } // This code is contributed by nitin mittal. |
Javascript
<script> // A Javascript program to find all the Stepping Number in [n, m] // This function checks if an integer n is a Stepping Number function isStepNum(n) { // Initialize prevDigit with -1 let prevDigit = -1; // Iterate through all digits of n and compare difference // between value of previous and current digits while (n > 0) { // Get Current digit let curDigit = n % 10; // Single digit is consider as a // Stepping Number if (prevDigit == -1) prevDigit = curDigit; else { // Check if absolute difference between // prev digit and current digit is 1 if (Math.abs(prevDigit - curDigit) != 1) return false ; } prevDigit = curDigit; n = parseInt(n / 10, 10); } return true ; } // A brute force approach based function to find all // stepping numbers. function displaySteppingNumbers(n, m) { // Iterate through all the numbers from [N,M] // and check if it’s a stepping number. for (let i = n; i <= m; i++) if (isStepNum(i)) document.write(i + " " ); } let n = 0, m = 21; // Display Stepping Numbers in // the range [n, m] displaySteppingNumbers(n, m); // This code is contributed by mukesh07. </script> |
输出:
0 1 2 3 4 5 6 7 8 9 10 12 21
方法2:使用BFS/DFS
如何构建图表? 图中的每个节点表示一个步进数;如果V可以从U转化为V,那么从节点U到V将有一条有向边。(U和V是步进数)步进数V可以以下方式从U转化为步进数V。 最后一位 指U的最后一位(即U%10) 相邻号码 五、 可以是:
- U*10+lastDigit+1(邻居A)
- U*10+最后一位数字–1(邻居B)
通过应用上述操作,一个新数字被附加到U上,它要么是lastDigit-1,要么是lastDigit+1,因此由U形成的新数字V也是一个步进数。 因此,每个节点最多有两个相邻节点。 边缘案例: 当U的最后一位是 0 或 9
- 案例1: lastDigit为0:在这种情况下,只能追加数字“1”。
- 案例2: lastDigit是9:在这种情况下,只能追加数字“8”。
什么是源/起始节点?
- 每个单个数字都被视为一个步进数,因此bfs遍历每个数字将给出从该数字开始的所有步进数。
- 对[0,9]中的所有数字进行bfs/dfs遍历。
注: 对于节点0,在BFS遍历期间无需探索邻居,因为它将导致01、012、010,并且这些将由从节点1开始的BFS遍历覆盖。 查找从0到21的所有步进数的示例
-> 0 is a stepping Number and it is in the range so display it.-> 1 is a Stepping Number, find neighbors of 1 i.e., 10 and 12 and push them into the queueHow to get 10 and 12?Here U is 1 and last Digit is also 1 V = 10 + 0 = 10 ( Adding lastDigit - 1 )V = 10 + 2 = 12 ( Adding lastDigit + 1 )Then do the same for 10 and 12 this will result into101, 123, 121 but these Numbers are out of range. Now any number transformed from 10 and 12 will resultinto a number greater than 21 so no need to explore their neighbors.-> 2 is a Stepping Number, find neighbors of 2 i.e. 21, 23.-> 23 is out of range so it is not considered as a Stepping Number (Or a neighbor of 2)The other stepping numbers will be 3, 4, 5, 6, 7, 8, 9.
基于BFS的解决方案:
C++
// A C++ program to find all the Stepping Number from N=n // to m using BFS Approach #include<bits/stdc++.h> using namespace std; // Prints all stepping numbers reachable from num // and in range [n, m] void bfs( int n, int m, int num) { // Queue will contain all the stepping Numbers queue< int > q; q.push(num); while (!q.empty()) { // Get the front element and pop from the queue int stepNum = q.front(); q.pop(); // If the Stepping Number is in the range // [n, m] then display if (stepNum <= m && stepNum >= n) cout << stepNum << " " ; // If Stepping Number is 0 or greater than m, // no need to explore the neighbors if (num == 0 || stepNum > m) continue ; // Get the last digit of the currently visited // Stepping Number int lastDigit = stepNum % 10; // There can be 2 cases either digit to be // appended is lastDigit + 1 or lastDigit - 1 int stepNumA = stepNum * 10 + (lastDigit- 1); int stepNumB = stepNum * 10 + (lastDigit + 1); // If lastDigit is 0 then only possible digit // after 0 can be 1 for a Stepping Number if (lastDigit == 0) q.push(stepNumB); //If lastDigit is 9 then only possible //digit after 9 can be 8 for a Stepping //Number else if (lastDigit == 9) q.push(stepNumA); else { q.push(stepNumA); q.push(stepNumB); } } } // Prints all stepping numbers in range [n, m] // using BFS. void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) bfs(n, m, i); } //Driver program to test above function int main() { int n = 0, m = 21; // Display Stepping Numbers in the // range [n,m] displaySteppingNumbers(n,m); return 0; } |
JAVA
// A Java program to find all the Stepping Number in // range [n, m] import java.util.*; class Main { // Prints all stepping numbers reachable from num // and in range [n, m] public static void bfs( int n, int m, int num) { // Queue will contain all the stepping Numbers Queue<Integer> q = new LinkedList<Integer> (); q.add(num); while (!q.isEmpty()) { // Get the front element and pop from // the queue int stepNum = q.poll(); // If the Stepping Number is in // the range [n,m] then display if (stepNum <= m && stepNum >= n) { System.out.print(stepNum + " " ); } // If Stepping Number is 0 or greater // then m, no need to explore the neighbors if (stepNum == 0 || stepNum > m) continue ; // Get the last digit of the currently // visited Stepping Number int lastDigit = stepNum % 10 ; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 int stepNumA = stepNum * 10 + (lastDigit- 1 ); int stepNumB = stepNum * 10 + (lastDigit + 1 ); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0 ) q.add(stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9 ) q.add(stepNumA); else { q.add(stepNumA); q.add(stepNumB); } } } // Prints all stepping numbers in range [n, m] // using BFS. public static void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) bfs(n, m, i); } //Driver code public static void main(String args[]) { int n = 0 , m = 21 ; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); } } |
Python3
# A Python3 program to find all the Stepping Number from N=n # to m using BFS Approach # Prints all stepping numbers reachable from num # and in range [n, m] def bfs(n, m, num) : # Queue will contain all the stepping Numbers q = [] q.append(num) while len (q) > 0 : # Get the front element and pop from the queue stepNum = q[ 0 ] q.pop( 0 ); # If the Stepping Number is in the range # [n, m] then display if (stepNum < = m and stepNum > = n) : print (stepNum, end = " " ) # If Stepping Number is 0 or greater than m, # no need to explore the neighbors if (num = = 0 or stepNum > m) : continue # Get the last digit of the currently visited # Stepping Number lastDigit = stepNum % 10 # There can be 2 cases either digit to be # appended is lastDigit + 1 or lastDigit - 1 stepNumA = stepNum * 10 + (lastDigit - 1 ) stepNumB = stepNum * 10 + (lastDigit + 1 ) # If lastDigit is 0 then only possible digit # after 0 can be 1 for a Stepping Number if (lastDigit = = 0 ) : q.append(stepNumB) #If lastDigit is 9 then only possible #digit after 9 can be 8 for a Stepping #Number elif (lastDigit = = 9 ) : q.append(stepNumA) else : q.append(stepNumA) q.append(stepNumB) # Prints all stepping numbers in range [n, m] # using BFS. def displaySteppingNumbers(n, m) : # For every single digit Number 'i' # find all the Stepping Numbers # starting with i for i in range ( 10 ) : bfs(n, m, i) # Driver code n, m = 0 , 21 # Display Stepping Numbers in the # range [n,m] displaySteppingNumbers(n, m) # This code is contributed by divyeshrabadiya07. |
C#
// A C# program to find all the Stepping Number in // range [n, m] using System; using System.Collections.Generic; public class GFG { // Prints all stepping numbers reachable from num // and in range [n, m] static void bfs( int n, int m, int num) { // Queue will contain all the stepping Numbers Queue< int > q = new Queue< int >(); q.Enqueue(num); while (q.Count != 0) { // Get the front element and pop from // the queue int stepNum = q.Dequeue(); // If the Stepping Number is in // the range [n,m] then display if (stepNum <= m && stepNum >= n) { Console.Write(stepNum + " " ); } // If Stepping Number is 0 or greater // then m, no need to explore the neighbors if (stepNum == 0 || stepNum > m) continue ; // Get the last digit of the currently // visited Stepping Number int lastDigit = stepNum % 10; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 int stepNumA = stepNum * 10 + (lastDigit- 1); int stepNumB = stepNum * 10 + (lastDigit + 1); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0) q.Enqueue(stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9) q.Enqueue(stepNumA); else { q.Enqueue(stepNumA); q.Enqueue(stepNumB); } } } // Prints all stepping numbers in range [n, m] // using BFS. static void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) bfs(n, m, i); } // Driver code static public void Main () { int n = 0, m = 21; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); } } // This code is contributed by avanitrachhadiya2155 |
Javascript
<script> // A Javascript program to find all // the Stepping Number in // range [n, m] // Prints all stepping numbers // reachable from num // and in range [n, m] function bfs(n,m,num) { // Queue will contain all the // stepping Numbers let q = []; q.push(num); while (q.length!=0) { // Get the front element and pop from // the queue let stepNum = q.shift(); // If the Stepping Number is in // the range [n,m] then display if (stepNum <= m && stepNum >= n) { document.write(stepNum + " " ); } // If Stepping Number is 0 or greater // then m, no need to explore the neighbors if (stepNum == 0 || stepNum > m) continue ; // Get the last digit of the currently // visited Stepping Number let lastDigit = stepNum % 10; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 let stepNumA = stepNum * 10 + (lastDigit- 1); let stepNumB = stepNum * 10 + (lastDigit + 1); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0) q.push(stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9) q.push(stepNumA); else { q.push(stepNumA); q.push(stepNumB); } } } // Prints all stepping numbers in range [n, m] // using BFS. function displaySteppingNumbers(n,m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for (let i = 0 ; i <= 9 ; i++) bfs(n, m, i); } // Driver code let n = 0, m = 21; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); // This code is contributed by unknown2108 </script> |
输出 :
0 1 10 12 2 21 3 4 5 6 7 8 9
基于DFS的解决方案
C++
// A C++ program to find all the Stepping Numbers // in range [n, m] using DFS Approach #include<bits/stdc++.h> using namespace std; // Prints all stepping numbers reachable from num // and in range [n, m] void dfs( int n, int m, int stepNum) { // If Stepping Number is in the // range [n,m] then display if (stepNum <= m && stepNum >= n) cout << stepNum << " " ; // If Stepping Number is 0 or greater // than m, then return if (stepNum == 0 || stepNum > m) return ; // Get the last digit of the currently // visited Stepping Number int lastDigit = stepNum % 10; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 int stepNumA = stepNum*10 + (lastDigit-1); int stepNumB = stepNum*10 + (lastDigit+1); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0) dfs(n, m, stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9) dfs(n, m, stepNumA); else { dfs(n, m, stepNumA); dfs(n, m, stepNumB); } } // Method displays all the stepping // numbers in range [n, m] void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) dfs(n, m, i); } //Driver program to test above function int main() { int n = 0, m = 21; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); return 0; } |
JAVA
// A Java program to find all the Stepping Numbers // in range [n, m] using DFS Approach import java.util.*; class Main { // Method display's all the stepping numbers // in range [n, m] public static void dfs( int n, int m, int stepNum) { // If Stepping Number is in the // range [n,m] then display if (stepNum <= m && stepNum >= n) System.out.print(stepNum + " " ); // If Stepping Number is 0 or greater // than m then return if (stepNum == 0 || stepNum > m) return ; // Get the last digit of the currently // visited Stepping Number int lastDigit = stepNum % 10 ; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 int stepNumA = stepNum* 10 + (lastDigit- 1 ); int stepNumB = stepNum* 10 + (lastDigit+ 1 ); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0 ) dfs(n, m, stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9 ) dfs(n, m, stepNumA); else { dfs(n, m, stepNumA); dfs(n, m, stepNumB); } } // Prints all stepping numbers in range [n, m] // using DFS. public static void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) dfs(n, m, i); } // Driver code public static void main(String args[]) { int n = 0 , m = 21 ; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); } } |
Python3
# A Python3 program to find all the Stepping Numbers # in range [n, m] using DFS Approach # Prints all stepping numbers reachable from num # and in range [n, m] def dfs(n, m, stepNum) : # If Stepping Number is in the # range [n,m] then display if (stepNum < = m and stepNum > = n) : print (stepNum, end = " " ) # If Stepping Number is 0 or greater # than m, then return if (stepNum = = 0 or stepNum > m) : return # Get the last digit of the currently # visited Stepping Number lastDigit = stepNum % 10 # There can be 2 cases either digit # to be appended is lastDigit + 1 or # lastDigit - 1 stepNumA = stepNum * 10 + (lastDigit - 1 ) stepNumB = stepNum * 10 + (lastDigit + 1 ) # If lastDigit is 0 then only possible # digit after 0 can be 1 for a Stepping # Number if (lastDigit = = 0 ) : dfs(n, m, stepNumB) # If lastDigit is 9 then only possible # digit after 9 can be 8 for a Stepping # Number elif (lastDigit = = 9 ) : dfs(n, m, stepNumA) else : dfs(n, m, stepNumA) dfs(n, m, stepNumB) # Method displays all the stepping # numbers in range [n, m] def displaySteppingNumbers(n, m) : # For every single digit Number 'i' # find all the Stepping Numbers # starting with i for i in range ( 10 ) : dfs(n, m, i) n, m = 0 , 21 # Display Stepping Numbers in # the range [n,m] displaySteppingNumbers(n, m) # This code is contributed by divyesh072019. |
C#
// A C# program to find all the Stepping Numbers // in range [n, m] using DFS Approach using System; public class GFG { // Method display's all the stepping numbers // in range [n, m] static void dfs( int n, int m, int stepNum) { // If Stepping Number is in the // range [n,m] then display if (stepNum <= m && stepNum >= n) Console.Write(stepNum + " " ); // If Stepping Number is 0 or greater // than m then return if (stepNum == 0 || stepNum > m) return ; // Get the last digit of the currently // visited Stepping Number int lastDigit = stepNum % 10; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 int stepNumA = stepNum*10 + (lastDigit - 1); int stepNumB = stepNum*10 + (lastDigit + 1); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0) dfs(n, m, stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9) dfs(n, m, stepNumA); else { dfs(n, m, stepNumA); dfs(n, m, stepNumB); } } // Prints all stepping numbers in range [n, m] // using DFS. public static void displaySteppingNumbers( int n, int m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for ( int i = 0 ; i <= 9 ; i++) dfs(n, m, i); } // Driver code static public void Main () { int n = 0, m = 21; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); } } // This code is contributed by rag2127. |
Javascript
<script> // A Javascript program to find all the Stepping Numbers // in range [n, m] using DFS Approach // Method display's all the stepping numbers // in range [n, m] function dfs(n, m, stepNum) { // If Stepping Number is in the // range [n,m] then display if (stepNum <= m && stepNum >= n) document.write(stepNum + " " ); // If Stepping Number is 0 or greater // than m then return if (stepNum == 0 || stepNum > m) return ; // Get the last digit of the currently // visited Stepping Number let lastDigit = stepNum % 10; // There can be 2 cases either digit // to be appended is lastDigit + 1 or // lastDigit - 1 let stepNumA = stepNum*10 + (lastDigit-1); let stepNumB = stepNum*10 + (lastDigit+1); // If lastDigit is 0 then only possible // digit after 0 can be 1 for a Stepping // Number if (lastDigit == 0) dfs(n, m, stepNumB); // If lastDigit is 9 then only possible // digit after 9 can be 8 for a Stepping // Number else if (lastDigit == 9) dfs(n, m, stepNumA); else { dfs(n, m, stepNumA); dfs(n, m, stepNumB); } } // Prints all stepping numbers in range [n, m] // using DFS. function displaySteppingNumbers(n, m) { // For every single digit Number 'i' // find all the Stepping Numbers // starting with i for (let i = 0 ; i <= 9 ; i++) dfs(n, m, i); } // Driver code let n = 0, m = 21; // Display Stepping Numbers in // the range [n,m] displaySteppingNumbers(n,m); // This code is contributed by ab2127 </script> |
输出:
0 1 10 12 2 21 3 4 5 6 7 8 9
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