Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = -123, return -321 ~~~ public class Solution { public int reverse(int x) { int negative=1; //负数先转正，用negative保存其符号 if( x<0 ) { negative = -1; x = -x; } long y = x%10; while( x/10 != 0 ) { x /= 10; y *= 10; y += x%10; } //if(y>Integer.MAX_VALUE) { if(y>Integer.MAX_VALUE||y<Integer.MIN_VALUE) { //return -1; return 0; } else { return (int) (negative*y); } } } ~~~