Merge pull request kothariji#604 from Kowsihan-sk/backTracking

added combination sum in Back tracking

Author: kothariji

Backtracking/Combination_sum_1.cpp

@@ -0,0 +1,29 @@
+class Solution {
+public:
+    void dfs(int ind, int t, vector<int> v, vector<int> &ar, vector<vector<int>> &ans){
+        if(t < 0) return;
+        if(t == 0){
+            ans.push_back(v);
+            return;
+        }
+        if(ind < 0) return;
+        
+        if(ar[ind] <= t){
+            v.push_back(ar[ind]);
+            dfs(ind, t - ar[ind], v, ar, ans);
+            v.pop_back();
+        }
+        
+        dfs(ind - 1, t, v, ar, ans);
+        
+    }
+    
+    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
+        vector<vector<int>> ans;
+        // sort(candidates.begin(), candidates.end());
+        
+        dfs(candidates.size() - 1, target, {}, candidates, ans);
+        
+        return ans;
+    }
+};

Backtracking/Combination_sum_2.cpp

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    void dfs(int ind, int t, vector<int> v, vector<int> &ar, vector<vector<int>> &ans){
+        if(t < 0) return;
+        if(t == 0){
+            ans.push_back(v);
+            return;
+        }
+        if(ind >= ar.size()) return;
+        
+        for(int i = ind; i < ar.size(); i++){
+            if((i != ind && ar[i] == ar[i-1] ) || ar[i] > t) continue;
+            v.push_back(ar[i]);
+            dfs(i + 1, t - ar[i], v, ar, ans);
+            v.pop_back();
+        }
+        
+    }
+    
+    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
+        vector<vector<int>> ans;
+        sort(candidates.begin(), candidates.end());
+        
+        dfs(0, target, {}, candidates, ans);
+        
+        return ans;
+    }
+};