add Combination Sum solution

Author: HoonDongKang

combination-sum/HoonDongKang.ts

@@ -0,0 +1,54 @@
+/**
+ * [Problem]: [39] Combination Sum
+ *
+ * (https://leetcode.com/problems/combination-sum/description/)
+ */
+function combinationSum(candidates: number[], target: number): number[][] {
+    // 시간복잡도: O(c^t)
+    // 공간복잡도 O(t)
+    function dfsFunc(candidates: number[], target: number): number[][] {
+        let result: number[][] = [];
+        let nums: number[] = [];
+
+        function dfs(start: number, total: number): void | number[][] {
+            if (total > target) return;
+            if (total === target) {
+                result.push([...nums]);
+                return result;
+            }
+            for (let i = start; i < candidates.length; i++) {
+                let num = candidates[i];
+                nums.push(num);
+                dfs(i, total + num);
+                nums.pop();
+            }
+        }
+
+        dfs(0, 0);
+        return result;
+    }
+
+    // 시간복잡도: O(c*t)
+    // 공간복잡도 O(c*t)
+    function dpFunc(candidates: number[], target: number): number[][] {
+        const dp: number[][][] = Array(target + 1)
+            .fill(null)
+            .map(() => []);
+
+        dp[0] = [[]];
+
+        for (const num of candidates) {
+            for (let t = num; t <= target; t++) {
+                for (const comb of dp[t - num]) {
+                    dp[t].push([...comb, num]);
+                }
+            }
+        }
+
+        return dp[target];
+    }
+
+    return dpFunc(candidates, target);
+}
+
+console.log(combinationSum([2, 3, 6, 7], 7));