add new solutions

solutions/0/q39/solution.go

@@ -0,0 +1,30 @@
+package q39
+
+import "slices"
+
+func mkCombs(candidates []int, target int, buf []int, ret [][]int) [][]int {
+	if target == 0 {
+		cp := make([]int, len(buf))
+		copy(cp, buf)
+		return append(ret, buf)
+	}
+	if len(candidates) == 0 || candidates[0] > target {
+		return ret
+	}
+	for i := 0; candidates[0]*i <= target; i++ {
+		ret = mkCombs(candidates[1:], target-i*candidates[0], buf, ret)
+		buf = append(buf, candidates[0])
+	}
+	return ret
+}
+
+func combinationSum(candidates []int, target int) [][]int {
+	slices.Sort(candidates)
+
+	ret := make([][]int, 0, 150)
+	buf := make([]int, target/candidates[0]+1)
+
+	return mkCombs(candidates, target, buf[:0], ret)
+}
+
+var _ = combinationSum