如果共线点不超过两个，则平面中三角形的数量-yiteyi-C++库

给定平面上的n个点，且共线点不超过两个，任务是计算给定平面上的三角形数。 例如：

null

Input :  n = 3Output : 1Input :  n = 4Output : 4

Number of Triangles

假设一个平面上有n个点，且没有三个或更多点共线，那么给定平面上的三角形数由 $^{n} extrm{C}_{3} = frac{n(n-1)(n-2)}{6}$

C++

                         // C++ program to find the number of                       
                         // triangles in a plane if no more                       
                         // then two points are collinear.                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // Function to find number of triangles                       
                         // in a plane.                       
                         int                                     countNumberOfTriangles(                                     int                                     n)                       
                         {                       
           
                                                 // Formula to find number of triangles                       
                                                 // nC3 = n * (n - 1) * (n - 2) / 6                       
                                                 return                                     n * (n - 1) * (n - 2) / 6;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 4;                       
                                                 cout << countNumberOfTriangles(n);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find the number of                       
                         // triangles in a plane if no more                       
                         // then two points are collinear.                       
                         import                                     java.io.*;                       
           
                         class                                     GFG {                       
           
                                                 // Function to find number of triangles                       
                                                 // in a plane.                       
                                                 static                                     int                                     countNumberOfTriangles(                                     int                                     n)                       
                                                 {                       
           
                                                 // Formula to find number of triangle                       
                                                 // nC3 = n * (n - 1) * (n - 2) / 6                       
                                                 return                                     n * (n -                                     1                                     ) * (n -                                     2                                     ) /                                     6                                     ;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     n =                                     4                                     ;                       
           
                                                 System.out.println(                       
                                                 countNumberOfTriangles(n));                       
                                                 }                       
                         }                       

Python3

                         # Python3 program to find                       
                         # the number of triangles                       
                         # in a plane if no more                       
                         # then two points are collinear.                       
           
                         # Function to find number                       
                         # of triangles in a plane.                       
                         def                                     countNumberOfTriangles(n) :                       
                                   
                                                 # Formula to find                       
                                                 # number of triangles                       
                                                 # nC3 = n * (n - 1) *                       
                                                 # (n - 2) / 6                       
                                                 return                                     (n                                     *                                     (n                                     -                                     1                                     )                                     *                       
                                                 (n                                     -                                     2                                     )                                     /                                     /                                     6                                     )                       
           
                         # Driver Code                       
                         if                                     __name__                                     =                                     =                                     '__main__'                                     :                       
                                   
                                                 n                                     =                                     4                       
                                                 print                                     (countNumberOfTriangles(n))                       
           
                                   
                         # This code is contributed                       
                         # by ajit                       

C#

                         // C# program to find the                       
                         // number of triangles in                       
                         // a plane if no more then                       
                         // two points are collinear.                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
           
                                                 // Function to find number                       
                                                 // of triangles in a plane.                       
                                                 static                                     int                                     countNumberOfTriangles(                                     int                                     n)                       
                                                 {                       
           
                                                 // Formula to find number                       
                                                 // of triangle                       
                                                 // nC3 = n * (n - 1) *                       
                                                 //           (n - 2) / 6                       
                                                 return                                     n * (n - 1) *                       
                                                 (n - 2) / 6;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 4;                       
           
                                                 Console.WriteLine(                       
                                                 countNumberOfTriangles(n));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by anuj_67.                       

PHP

                         <?php                       
                         // PHP program to find the                       
                         // number of triangles in a                       
                         // plane if no more then                       
                         // two points are collinear.                       
           
                         // Function to find number                       
                         // of triangles in a plane.                       
                         function                                     countNumberOfTriangles(                                     $n                                     )                       
                         {                       
                                                 // Formula to find number                       
                                                 // of triangles nC3 = n *                       
                                                 // (n - 1) * (n - 2) / 6                       
                                                 return                                     $n                                     * (                                     $n                                     - 1) *                       
                                                 (                                     $n                                     - 2) / 6;                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 4;                       
                         echo                                     countNumberOfTriangles(                                     $n                                     );                       
           
                         // This code is contributed                       
                         // by anuj_67.                       
                         ?>                       

Javascript

                         <script>                       
                         // javascript program to find the number of                       
                         // triangles in a plane if no more                       
                         // then two points are collinear.                       
           
                                                 // Function to find number of triangles                       
                                                 // in a plane.                       
                                                 function                                     countNumberOfTriangles(n)                       
                                                 {                       
           
                                                 // Formula to find number of triangle                       
                                                 // nC3 = n * (n - 1) * (n - 2) / 6                       
                                                 return                                     n * (n - 1) * (n - 2) / 6;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 var                                     n = 4;                       
                                                 document.write(countNumberOfTriangles(n));                       
           
                         // This code is contributed by aashish1995                       
                         </script>                       

输出：

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