Combination Sum solution

Author: kim-young

combination-sum/kimyoung.js

@@ -0,0 +1,29 @@
+var combinationSum = function (candidates, target) {
+    let results = [];
+
+    function helper(idx, curr, total) {
+        // base case - when total = target push into results
+        if (total === target) {
+            results.push([...curr]);
+            return;
+        }
+        // base exit case - when the index is greater or equal to candidates or the total is greater than target, exit
+        if (idx >= candidates.length || total > target) {
+            return;
+        }
+
+        // recursive case
+        // case where we include the current value without advancing the index
+        curr.push(candidates[idx]);
+        helper(idx, curr, total + candidates[idx]);
+        curr.pop()
+        // case where we advance the index 
+        helper(idx + 1, curr, total);
+    }
+    helper(0, [], 0);
+    
+    return results;
+};
+
+// time - O(2^n) backtracking
+// space - O(1)