fix fucking int32 test case

Author: hitzzc

reverse_integer/reverse_integer.go

@@ -1,21 +1,36 @@
 package reverse_integer
 
+// fucking leetcode's int32 overflow test cases
+const (
+	MAX int32 = 1<<31 - 1
+	MIN       = -MAX - 1
+)
+
 func reverse(x int) int {
-	sign := 1
+	var sign int32 = 1
 	tmp := x
 	if x < 0 {
 		sign = -1
 		tmp = -1 * x
 	}
-	list := []int{}
+	list := []int32{}
 	for tmp > 9 {
-		list = append(list, tmp%10)
+		list = append(list, int32(tmp%10))
 		tmp = tmp / 10
 	}
-	list = append(list, tmp)
-	ret := 0
+	list = append(list, int32(tmp))
+	var ret int32
 	for i := 0; i < len(list); i++ {
+		if sign == 1 {
+			if ret > (MAX-list[i])/10 {
+				return 0
+			}
+		} else {
+			if -ret < (MIN+list[i])/10 {
+				return 0
+			}
+		}
 		ret = 10*ret + list[i]
 	}
-	return ret * sign
+	return int(ret * sign)
 }

reverse_integer/reverse_integer_test.go

@@ -17,7 +17,7 @@ func TestReverse(t *testing.T) {
 		-321,
 		0,
 		-1,
-		9646324351,
+		0,
 	}
 	caseNum := 5
 	for i := 0; i < caseNum; i++ {