From 62194f5fbc5a5352304d8eb6a0d4e44a346b546c Mon Sep 17 00:00:00 2001
From: tiennm99 <tiennm99@outlook.com>
Date: Sun, 7 Dec 2025 11:02:09 +0700
Subject: [PATCH] Update exam.go

---
 go/exam/exam.go | 47 +++++++++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/go/exam/exam.go b/go/exam/exam.go
index 4023d02..5cea475 100644
--- a/go/exam/exam.go
+++ b/go/exam/exam.go
@@ -23,18 +23,17 @@ func calc(a int64, op byte, b int64) int64 {
 	return a * b
 }
 
+func ts(x int64) string {
+	return strconv.FormatInt(x, 10)
+}
+
 func getAll(nums []int64, ops []byte) []Pair {
 	sz := len(nums)
-	var result []Pair
-	seen := make(map[int64]bool)
-
-	ts := func(x int64) string {
-		return strconv.FormatInt(x, 10)
-	}
+	var all []Pair
 
 	if sz == 2 {
 		v := calc(nums[0], ops[0], nums[1])
-		result = append(result, Pair{v, ts(nums[0]) + string(ops[0]) + ts(nums[1])})
+		all = append(all, Pair{v, ts(nums[0]) + string(ops[0]) + ts(nums[1])})
 	} else if sz == 3 {
 		a, b, c := nums[0], nums[1], nums[2]
 		o1, o2 := ops[0], ops[1]
@@ -42,29 +41,32 @@ func getAll(nums []int64, ops []byte) []Pair {
 		v2 := calc(calc(a, o1, b), o2, c)
 		s1 := ts(a) + string(o1) + "(" + ts(b) + string(o2) + ts(c) + ")"
 		s2 := "(" + ts(a) + string(o1) + ts(b) + ")" + string(o2) + ts(c)
-		result = append(result, Pair{v1, s1})
-		seen[v1] = true
-		if !seen[v2] {
-			seen[v2] = true
-			result = append(result, Pair{v2, s2})
-		}
+		all = append(all, Pair{v1, s1}, Pair{v2, s2})
 	} else {
 		a, b, c, d := nums[0], nums[1], nums[2], nums[3]
 		o1, o2, o3 := ops[0], ops[1], ops[2]
-		all := []Pair{
+		all = []Pair{
 			{calc(a, o1, calc(b, o2, calc(c, o3, d))), ts(a) + string(o1) + "(" + ts(b) + string(o2) + "(" + ts(c) + string(o3) + ts(d) + "))"},
 			{calc(a, o1, calc(calc(b, o2, c), o3, d)), ts(a) + string(o1) + "((" + ts(b) + string(o2) + ts(c) + ")" + string(o3) + ts(d) + ")"},
 			{calc(calc(a, o1, b), o2, calc(c, o3, d)), "(" + ts(a) + string(o1) + ts(b) + ")" + string(o2) + "(" + ts(c) + string(o3) + ts(d) + ")"},
 			{calc(calc(a, o1, calc(b, o2, c)), o3, d), "(" + ts(a) + string(o1) + "(" + ts(b) + string(o2) + ts(c) + "))" + string(o3) + ts(d)},
 			{calc(calc(calc(a, o1, b), o2, c), o3, d), "((" + ts(a) + string(o1) + ts(b) + ")" + string(o2) + ts(c) + ")" + string(o3) + ts(d)},
 		}
-		for _, p := range all {
-			if !seen[p.val] {
-				seen[p.val] = true
-				result = append(result, p)
-			}
+	}
+
+	sort.SliceStable(all, func(i, j int) bool {
+		return all[i].val < all[j].val
+	})
+
+	var result []Pair
+	seen := make(map[int64]bool)
+	for _, p := range all {
+		if !seen[p.val] {
+			seen[p.val] = true
+			result = append(result, p)
 		}
 	}
+
 	return result
 }
 
@@ -102,8 +104,13 @@ func exam(in *os.File, out *os.File) {
 	for i := 0; i < n; i++ {
 		order[i] = i
 	}
+
 	sort.Slice(order, func(i, j int) bool {
-		return len(exprs[order[i]]) < len(exprs[order[j]])
+		li, lj := len(exprs[order[i]]), len(exprs[order[j]])
+		if li != lj {
+			return li < lj
+		}
+		return order[i] < order[j]
 	})
 
 	result := make([]string, n)