[LeetCode]7.整数反转

class Solution {
    public int reverse(int x) {
        int res = 0;
        while(x != 0){
            int tmp = x%10;
             
            if(res > 214748364 || (res == 214748364 && tmp > 7))
                return 0;
            if(res < -214748364 || (res == -214748364 && tmp < -8))
                return 0;

            res = res*10 +tmp;
            x /= 10;
        }
        return res;
      
    }
}

基本的整数取反模块

int res = 0;
while(x != 0){
	int tmp = x%10; //取末尾数字
	res = res*10 + tmp;
	x /= 10;
}

32位整数的取值范围[-2^31, 2^31 - 1]

2^31 = 2147483648

最小数为 -2147483648

最大数为 2147483647