方阵两对角线上的行公共元素-yiteyi-C++库

给定一个方阵，找出同一行中相同的数，以及主对角线和次对角线中相同的数。 例如：

null

Input : 1 2 1        4 5 2        0 5 1Output : 2Primary diagonal is 1 5 1Secondary diagonal is 1 5 0Two elements (1 and 5) match in two diagonals and same.Input : 1 0 0        0 1 0        0 0 1Output : 1Primary diagonal is 1 1 1Secondary diagonal is 0 1 0Only one element is same.

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

我们可以在O（n）时间、O（1）空间和一次遍历中实现这一点。我们可以在主对角线的第i行找到当前元素mat[i][i]，在次对角线的第i行找到元素mat[i][n-i-1]。

C++

                         // CPP program to find common elements in                       
                         // two diagonals.                       
                         #include <iostream>                       
                         #define MAX 100                       
                         using                                     namespace                                     std;                       
           
                         // Returns count of row wise same                       
                         // elements in two diagonals of                       
                         // mat[n][n]                       
                         int                                     countCommon(                                     int                                     mat[][MAX],                                     int                                     n)                       
                         {                       
                                                 int                                     res = 0;                       
                                                 for                                     (                                     int                                     i=0;i<n;i++)                       
                                                 if                                     (mat[i][i] == mat[i][n-i-1])                       
                                                 res++;                       
                                                 return                                     res;                       
                         }                       
           
                         // Driver Code                       
                         int                                     main()                       
                         {                       
                                                 int                                     mat[][MAX] = {{1, 2, 3},                       
                                                 {4, 5, 6},                       
                                                 {7, 8, 9}};                       
                                                 cout << countCommon(mat, 3);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find common                       
                         // elements in two diagonals.                       
                         import                                     java.io.*;                       
           
                         class                                     GFG                       
                         {                       
                                                 int                                     MAX =                                     100                                     ;                       
                                   
                                                 // Returns count of row wise same elements                       
                                                 // in two diagonals of mat[n][n]                       
                                                 static                                     int                                     countCommon(                                     int                                     mat[][],                                     int                                     n)                       
                                                 {                       
                                                 int                                     res =                                     0                                     ;                       
                                                 for                                     (                                     int                                     i =                                     0                                     ; i < n; i++)                       
                                                 if                                     (mat[i][i] == mat[i][n - i -                                     1                                     ])                       
                                                 res++;                       
                                                 return                                     res;                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main(String args[])                                     throws                                     IOException                       
                                                 {                       
                                                 int                                     mat[][] = {{                                     1                                     ,                                     2                                     ,                                     3                                     },                       
                                                 {                                     4                                     ,                                     5                                     ,                                     6                                     },                       
                                                 {                                     7                                     ,                                     8                                     ,                                     9                                     }};                       
                                                 System.out.println(countCommon(mat,                                     3                                     ));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Anshika Goyal.                       

Python3

                         # Python3 program to find common                       
                         # elements in two diagonals.                       
           
                         Max                                     =                                     100                       
           
                         # Returns count of row wise same                       
                         # elements in two diagonals of                       
                         # mat[n][n]                       
                         def                                     countCommon(mat, n):                       
                                                 res                                     =                                     0                       
                                   
                                                 for                                     i                                     in                                     range                                     (n):                       
                                   
                                                 if                                     mat[i][i]                                     =                                     =                                     mat[i][n                                     -                                     i                                     -                                     1                                     ] :                       
                                                 res                                     =                                     res                                     +                                     1                       
                                                 return                                     res                       
           
                         # Driver Code                       
                         mat                                     =                                     [[                                     1                                     ,                                     2                                     ,                                     3                                     ],                       
                                                 [                                     4                                     ,                                     5                                     ,                                     6                                     ],                       
                                                 [                                     7                                     ,                                     8                                     ,                                     9                                     ]]                       
           
                         print                                     (countCommon(mat,                                     3                                     ))                       
           
                         # This code is contributed by Anant Agarwal.                       

C#

                         // C# program to find common                       
                         // elements in two diagonals.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                                                 // Returns count of row wise same                       
                                                 // elements in two diagonals of                       
                                                 // mat[n][n]                       
                                                 static                                     int                                     countCommon(                                     int                                     [,]mat,                                     int                                     n)                       
                                                 {                       
                                                 int                                     res = 0;                       
                                   
                                                 for                                     (                                     int                                     i = 0; i < n; i++)                       
                                                 if                                     (mat[i,i] == mat[i,n - i - 1])                       
                                                 res++;                       
                                   
                                                 return                                     res;                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     [,]mat = {{1, 2, 3},                       
                                                 {4, 5, 6},                       
                                                 {7, 8, 9}};                       
                                                 Console.WriteLine(countCommon(mat, 3));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m.                       

PHP

                         <?php                       
                         // PHP program to find common                       
                         // elements in two diagonals.                       
                         $MAX                                     = 100;                       
           
                         // Returns count of row wise                       
                         // same elements in two                       
                         // diagonals of mat[n][n]                       
                         function                                     countCommon(                                     $mat                                     ,                                     $n                                     )                       
                         {                       
                                                 global                                     $MAX                                     ;                       
                                                 $res                                     = 0;                       
                                                 for                                     (                                     $i                                     = 0;                                     $i                                     <                                     $n                                     ;                                     $i                                     ++)                       
                                                 if                                     (                                     $mat                                     [                                     $i                                     ][                                     $i                                     ] ==                                     $mat                                     [                                     $i                                     ][                                     $n                                     -                                     $i                                     - 1])                       
                                                 $res                                     ++;                       
                                                 return                                     $res                                     ;                       
                         }                       
           
                         // Driver Code                       
                         $mat                                     =                                     array                                     (                                     array                                     (1, 2, 3),                       
                                                 array                                     (4, 5, 6),                       
                                                 array                                     (7, 8, 9));                       
                         echo                                     countCommon(                                     $mat                                     , 3);                       
           
                         // This code is contributed by aj_36                       
                         ?>                       

Javascript

                         <script>                       
                         // Javascript program to find common elements in                       
                         // two diagonals.                       
                         let MAX = 100;                       
           
                         // Returns count of row wise same                       
                         // elements in two diagonals of                       
                         // mat[n][n]                       
                         function                                     countCommon(mat, n)                       
                         {                       
                                                 let res = 0;                       
                                                 for                                     (let i = 0; i < n; i++)                       
                                                 if                                     (mat[i][i] == mat[i][n - i - 1])                       
                                                 res++;                       
                                                 return                                     res;                       
                         }                       
           
                         // Driver Code                       
                                                 let mat = [[1, 2, 3],                       
                                                 [4, 5, 6],                       
                                                 [7, 8, 9]];                       
                                                 document.write(countCommon(mat, 3));                       
           
                         // This code is contributed by subham348.                       
                         </script>                       

输出：

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