two-sum: sort version

Author: Invidam

two-sum/invidam.go

@@ -1,9 +1,29 @@
+type NumAndIdx struct {
+	Num int
+	Idx int
+}
+
 func twoSum(nums []int, target int) []int {
-	for i, ni := range nums {
-		for j, nj := range nums {
-			if i != j && ni+nj == target {
-				return []int{i, j}
-			}
+	numAndIdxs := make([]NumAndIdx, 0, len(nums))
+	for i, n := range nums {
+		numAndIdxs = append(numAndIdxs, NumAndIdx{Num: n, Idx: i})
+	}
+
+	sort.Slice(numAndIdxs, func(i, j int) bool {
+		return numAndIdxs[i].Num < numAndIdxs[j].Num
+	})
+
+	ldx, rdx := 0, len(numAndIdxs)-1
+
+	for ldx < rdx {
+		l := numAndIdxs[ldx]
+		r := numAndIdxs[rdx]
+		if sum := l.Num + r.Num; sum > target {
+			rdx--
+		} else if sum < target {
+			ldx++
+		} else {
+			return []int{l.Idx, r.Idx}
 		}
 	}