﻿ C exercises: Find all unique triplets in a given array integers whose sum equal to zero - w3resource

# C Exercises: Find all unique triplets in a given array integers whose sum equal to zero

## C Programming Practice: Exercise-8 with Solution

Write a C programming to find all unique triplets in a given array integers whose sum equal to zero.

C Code:

``````#include <stdio.h>
#include <stdlib.h>
static int compare_two_num(const void *a, const void *b)
{
return *(int *) a - *(int *) b;
}
static void two_sum(int *nums, int low_pos, int high_pos, int target, int **results, int *ctr)
{
while (low_pos < high_pos) {
int diff = target - nums[low_pos];
if (diff > nums[high_pos]) {
while (++low_pos < high_pos && nums[low_pos] == nums[low_pos - 1]) {}
} else if (diff < nums[high_pos]) {
while (--high_pos > low_pos && nums[high_pos] == nums[high_pos + 1]) {}
} else {
results[*ctr] = malloc(3 * sizeof(int));
results[*ctr][0] = -target;
results[*ctr][1] = nums[low_pos];
results[*ctr][2] = nums[high_pos];
(*ctr)++;
while (++low_pos < high_pos && nums[low_pos] == nums[low_pos - 1]) {}
while (--high_pos > low_pos && nums[high_pos] == nums[high_pos + 1]) {}
}
}
}
static int** three_Sum(int* nums, int numsSize, int* returnSize)
{
if (numsSize < 3) {
return NULL;
}
qsort(nums, numsSize, sizeof(*nums), compare_two_num);
*returnSize = 0;
int i, j, capacity = 50000;
int **results = malloc(capacity * sizeof(int *));
for (i = 0; i < numsSize; i++) {
if (i == 0 || i > 0 && nums[i] != nums[i - 1]) {
two_sum(nums, i + 1, numsSize - 1, -nums[i], results, returnSize);
}
}
return results;
}
int main(void)
{
int i, ctr;
int nums[] = {-2,0,0,1,1};
ctr = sizeof(nums) / sizeof(*nums);
printf("Original Array: ");
for(i=0; i<ctr; i++)
{
printf("%d  ", nums[i]);
}
int **result = three_Sum(nums, sizeof(nums) / sizeof(*nums), &ctr);
for (i = 0; i < ctr; i++) {
printf("\nUnique triplets of the said array whose sum equal to zero: ");
printf("%d %d %d\n", result[i][0], result[i][1], result[i][2]);
}
return 0;
}
``````

Sample Output:

```Original Array: -2  0  0  1  1
Unique triplets of the said array whose sum equal to zero: -2 1 1
```

Flowchart: 1

Flowchart: 2

## C Programming Code Editor:

What is the difficulty level of this exercise?

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## C Programming: Tips of the Day

The tilde operator in C:

The ~ operator is bitwise NOT, it inverts the bits in a binary number:

```NOT 011100
= 100011
```

Ref : https://bit.ly/3DR1N24