Update README.md

Author: yanglbme

solution/0000-0099/0008.String to Integer (atoi)/README.md

@@ -391,33 +391,28 @@ class Solution {
 ```C
 int myAtoi(char* s) {
     int i = 0;
-    int sign = 1;
-    long result = 0;
+
     while (s[i] == ' ') {
         i++;
     }
+
+    int sign = 1;
     if (s[i] == '-' || s[i] == '+') {
         sign = (s[i] == '-') ? -1 : 1;
         i++;
     }
+
+    int res = 0;
     while (isdigit(s[i])) {
-        result = result * 10 + (s[i] - '0');
-        if (sign == 1 && result > INT_MAX) {
-            return INT_MAX;
-        }
-        if (sign == -1 && -result < INT_MIN) {
-            return INT_MIN;
+        int digit = s[i] - '0';
+        if (res > INT_MAX / 10 || (res == INT_MAX / 10 && digit > INT_MAX % 10)) {
+            return sign == 1 ? INT_MAX : INT_MIN;
         }
+        res = res * 10 + digit;
         i++;
     }
-    b
-        result
-        *= sign;
-    if (result > INT_MAX)
-        return INT_MAX;
-    if (result < INT_MIN)
-        return INT_MIN;
-    return (int) result;
+
+    return res * sign;
 }
 ```