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:
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Previous: Write a C programming to convert a given roman number to an integer.
Next: Write a C program to find all unique quadruplets in a given array of integers whose sum equal to zero.
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C Programming: Tips of the Day
Static variable inside of a function in C
The scope of variable is where the variable name can be seen. Here, x is visible only inside function foo().
The lifetime of a variable is the period over which it exists. If x were defined without the keyword static, the lifetime would be from the entry into foo() to the return from foo(); so it would be re-initialized to 5 on every call.
The keyword static acts to extend the lifetime of a variable to the lifetime of the programme; e.g. initialization occurs once and once only and then the variable retains its value - whatever it has come to be - over all future calls to foo().
Ref : https://bit.ly/3fOq7XP
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