C Exercises: Count the number of triangles can be fromed from a given array
C Array: Exercise-52 with Solution
Write a program in C to count the number of triangles that can be formed from a given array.
Sample Solution:
C Code:
#include <stdio.h>
#include <stdlib.h>
// Comparison function for qsort
int compare(const void* one, const void* two)
{
return *(int*)one > *(int*)two; // Compare two integers
}
// Function to count the number of possible triangles that can be formed
int CountNumberOfTriangles(int *arr1, int arr_size)
{
int ctrTriangle = 0, i, j, k;
qsort(arr1, arr_size, sizeof(int), compare); // Sort the array in ascending order
for (i = 0; i < arr_size - 2; ++i)
{
for (j = i + 1; j < arr_size; ++j)
{
k = j + 1;
// Check for triangles (arr1[i] + arr1[j]) > arr1[k]
while (k < arr_size && (arr1[i] + arr1[j]) > arr1[k])
{
k++;
}
// Increment the count of triangles
ctrTriangle += k - j - 1;
}
}
return ctrTriangle;
}
int main()
{
int arr1[] = {6, 18, 9, 7, 10};
int n = sizeof(arr1) / sizeof(arr1[0]);
int i;
// Print the original array
printf("The given array is: ");
for (i = 0; i < n; i++)
{
printf("%d ", arr1[i]);
}
printf("\n");
// Calculate and print the number of possible triangles that can be formed from the array
printf("Number of possible triangles that can be formed from the array is: %d\n",
CountNumberOfTriangles(arr1, n));
return 0;
}
Sample Output:
The given array is : 6 18 9 7 10 Number of possible triangles can be formed from the array is: 5
Flowchart:

C Programming Code Editor:
Previous: Write a program in C to find the maximum circular subarray sum of a given array.
Next: Write a program in C to to print next greater elements in a given unsorted array. Elements for which no greater element exist, consider next greater element as -1.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
- Weekly Trends
- Python Interview Questions and Answers: Comprehensive Guide
- Scala Exercises, Practice, Solution
- Kotlin Exercises practice with solution
- MongoDB Exercises, Practice, Solution
- SQL Exercises, Practice, Solution - JOINS
- Java Basic Programming Exercises
- SQL Subqueries
- Adventureworks Database Exercises
- C# Sharp Basic Exercises
- SQL COUNT() with distinct
- JavaScript String Exercises
- JavaScript HTML Form Validation
- Java Collection Exercises
- SQL COUNT() function
- SQL Inner Join