combination-sum

Author: taewanseoul

combination-sum/taewanseoul.ts

@@ -0,0 +1,37 @@
+/**
+ * 39. Combination Sum
+ * Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.
+ * The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different.
+ * The test cases are generated such that the number of unique combinations that sum up to target is less than 150 combinations for the given input.
+ *
+ * https://leetcode.com/problems/combination-sum/description/
+ */
+
+// O(n^m) time
+// O(n) space
+function combinationSum(candidates: number[], target: number): number[][] {
+  const res: number[][] = [];
+  dfs(candidates, 0, target, [], res);
+  return res;
+}
+
+function dfs(
+  nums: number[],
+  start: number,
+  remaining: number,
+  path: number[],
+  res: number[][]
+) {
+  if (remaining === 0) {
+    res.push([...path]);
+    return;
+  }
+
+  for (let i = start; i < nums.length; i++) {
+    const num = nums[i];
+    if (remaining - num < 0) continue;
+    path.push(num);
+    dfs(nums, i, remaining - num, path, res);
+    path.pop();
+  }
+}