Backtracking solution for combinational Sum

Author: ranganeeraj

Dynamic Programming/Combinational Sum/SolutionByNeeraj.cpp

@@ -0,0 +1,62 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+ void findNumbers(vector<int>& ar, int sum, vector<vector<int> >& res, vector<int>& r, int i) {
+ if (sum == 0) {
+	res.push_back(r);
+ return;
+	}
+ while (i < ar.size() && sum - ar[i] >= 0) {
+
+	r.push_back(ar[i]);
+ findNumbers(ar, sum - ar[i], res, r, i);
+	i++;
+	r.pop_back();
+	}
+ }
+
+ vector<vector<int> > combinationSum(vector<int>& ar, int sum) {
+ sort(ar.begin(), ar.end());
+	ar.erase(unique(ar.begin(), ar.end()), ar.end());
+
+	vector<int> r;
+	vector<vector<int> > res;
+ findNumbers(ar, sum, res, r, 0);
+
+ return res;
+ }
+
+ int main() {
+ 
+ int n, sum;
+	cout << "Enter the size of array: ";
+	cin >> n;
+ 
+	vector<int> ar(n, 0);
+ 
+	cout << "Enter the elements of the array: ";
+ for (auto& i : ar) {
+ cin >> i;
+	}
+
+	cout << "Enter the required sum: ";
+	cin >> sum;
+ 
+	vector<vector<int> > res = combinationSum(ar, sum);
+
+ if (res.size() == 0) {
+	cout << "Empty";
+ return 0;
+	}
+ for (int i = 0; i < res.size(); i++) {
+ if (res[i].size() > 0) {
+	cout << "[";
+ for (int j = 0; j < res[i].size(); j++){
+	cout << res[i][j];
+ if (j<(res[i].size()-1))
+ cout << ", ";
+	}
+	cout << "]\n";
+	}
+	}
+ }