7.13 第一次做，不能 AC
7.14 不能 AC
7.15 差了一点，过吧！

题目描述

原题链接：https://leetcode-cn.com/problems/ba-zi-fu-chuan-zhuan-huan-cheng-zheng-shu-lcof/

解题思路

K 神题解：https://leetcode-cn.com/problems/ba-zi-fu-chuan-zhuan-huan-cheng-zheng-shu-lcof/solution/

• 数字字符转换成数字要记得减去字符 ‘0’

class Solution {
    public int strToInt(String str) {
        char[] c = str.trim().toCharArray();
        if(c.length == 0) return 0;
        int boundary = Integer.MAX_VALUE / 10, res = 0;
        int sign = 1, i = 1;
        if(c[0] == '-') sign = -1;       
        else if(c[0] != '+') i = 0;
        for(int j = i; j < c.length; j++) {
            if(c[j] < '0' || c[j] > '9') break;
            if(res > boundary || res == boundary && c[j] > '7') return sign == 1 ? Integer.MAX_VALUE : Integer.MIN_VALUE;
            res = res * 10 + (c[j] - '0');
        }
        return sign * res;
    }
}