Given a 32-bit signed integer x, return the result of inverting the numeric portion of x.
Returns 0 if the inverted integer exceeds the range [−231, 231 − 1] of a 32-bit signed integer.
Assume the environment does not allow storing 64-bit integers (signed or unsigned).
Example 1:
Input: x = 123
Output: 321
Example 2:
Input: x = -123
Output: -321
Example 3:
Input: x = 120
Output: 21
Example 4:
Input: x = 0
Output: 0
hint:
-231 <= x <= 231 - 1
Problem-solving ideas: Process according to the Number type, get the last digit of the original number each time, and gradually change it to a high digit. The last digit of the original number is removed every cycle, but manual rounding is required in js. Here, |0 is added after the number, that is, it is rounded toward 0, negative numbers are rounded toward zero, and positive integers are also rounded toward zero. all.
/**
* @param {number} x
* @return {number}
*/
var reverse = function(x) {
let result = 0;
while(x !== 0) {
result = result * 10 + x % 10; // 累加
x = x / 10 |0; // js取整操作，在后面加|0
console.log(x)
}
return result < -Math.pow(2,31)-1 || result > Math.pow(2,31) ? 0 : result;
};
If you don't do the rounding operation, you will always take decimals and keep taking decimals.
