LeetCode: Reverse Integer

Reverse Integer

*Reverse digits of an integer.

Example1: x = 123, return 321

Example2: x = -123, return -321

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Note:

The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

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解题过程 :

如果输入的是负数，我们先将他化为正数，最后再加上负号，将整数每个位置上的值都按顺序添加到一个数组中，然后用数组将他倒转，要保证倒转后的值不溢出，加一个判断溢出的条件就可以了，代码如下：

int reverse(int x) {
int s[32];
int i = 0;
int flag = 0;

if(x<0){
x = -x;
flag = 1;
}
while(x>0){
s[i] = x % 10;
x = (x - s[i]) / 10;
i++;
}

long long y = 0;
for(int j=0; j<i; j++ ){
y = s[j] * pow(10,i-j-1) + y;

}
if(y>2147483648 ){ return 0;}
if(flag == 0)
return y;
else return -y;
}