leetcode练习：2017/09/21~09/22

Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

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

var min_32 = 1<<31;
var max_32 = parseInt(‘7fffffff‘,16);
var reverse = function(x) {
    var syn=0;
    if(x < 0){
        x = Math.abs(x);
        syn=1;
    }

    x = x + "";
    var len = x.length;

    var arr = x.split(‘‘);
    for(var i=0; i<len/2; i++){
        var temp = x[i];
        arr.splice(i,1,x[len-i-1]);
        arr.splice(len-i-1,1,temp);
    }

    x = parseInt(arr.join(""));

    if(x> max_32) {
        return 0;
    }

    if(x< min_32){
      return 0;
    } 

    if(!syn)
        return x;
    else
        return -x;
};

Palindrome Number

Determine whether an integer is a palindrome. Do this without extra space.

var isPalindrome = function(x) {
    if(x<0) return false;
    var a = [];
    var n = 10;
    while(x>0){
        a.push(x%10);
        x = parseInt(x / 10);
    }
    var len = a.length;
    for(var i=0;i<len/2;i++){
      if(a[i] != a[len-1-i])
        return false;
    }
    return true;

};