Create heozeop.cpp

Author: heozeop

combination-sum/heozeop.cpp

@@ -0,0 +1,35 @@
+// Time Complexity: O(n)
+// Spatial Complexity: O(n);
+
+class Solution {
+public:
+  vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
+    vector<vector<int>> ans;
+    vector<int> visited;
+    backtrack(ans, candidates, visited, target, 0);
+    return ans;
+  }
+
+  void backtrack(
+    vector<vector<int>>& ans, 
+    vector<int>& candidates, 
+    vector<int>& visited,
+    int target,
+    int prev
+  ) {
+    if(target == 0) {
+      ans.push_back(visited);
+      return;
+    }
+
+    for(int i = prev; i < candidates.size(); ++i) {
+      if (target - candidates[i] < 0) {
+        continue;
+      }
+
+      visited.push_back(candidates[i]);
+      backtrack(ans, candidates, visited, target - candidates[i], i);
+      visited.pop_back();
+    }
+  }
+};