# C / C++ Program for Subset Sum (Backtracking)

Backtracking is a technique to solve dynamic programming problems. It works by going step by step and rejects those paths that do not lead to a solution and trackback (moves back ) to the previous position.

In the subset sum problem, we have to find the subset of a set is such a way that the element of this subset-sum up to a given number K. All the elements of the set are positive and unique (no duplicate elements are present).

For this, we will create subsets and check if their sum is equal to the given number k. Let's see a program to create a solution.

## Example

Live Demo

#include <stdio.h>
#include <stdlib.h>
static int total_nodes;
void printValues(int A[], int size){
for (int i = 0; i < size; i++) {
printf("%*d", 5, A[i]);
}
printf("\n");
}
void subset_sum(int s[], int t[], int s_size, int t_size, int sum, int ite, int const target_sum){
total_nodes++;
if (target_sum == sum) {
printValues(t, t_size);
subset_sum(s, t, s_size, t_size - 1, sum - s[ite], ite + 1, target_sum);
return;
}
else {
for (int i = ite; i < s_size; i++) {
t[t_size] = s[i];
subset_sum(s, t, s_size, t_size + 1, sum + s[i], i + 1, target_sum);
}
}
}
void generateSubsets(int s[], int size, int target_sum){
int* tuplet_vector = (int*)malloc(size * sizeof(int));
subset_sum(s, tuplet_vector, size, 0, 0, 0, target_sum);
free(tuplet_vector);
}
int main(){
int set[] = { 5, 6, 12 , 54, 2 , 20 , 15 };
int size = sizeof(set) / sizeof(set[0]);
printf("The set is ");
printValues(set , size);
generateSubsets(set, size, 25);
printf("Total Nodes generated %d\n", total_nodes);
return 0;
}

## Output

The set is 5 6 12 54 2 20 15
5 6 12 2
5 20
Total Nodes generated 127