題目
難度：easy
Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
Note:
The given integer is guaranteed to fit within the range of a 32-bit signed integer.
You could assume no leading zero bit in the integer’s binary representation.
Example 1:
Input: 5
Output: 2
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
Example 2:
Input: 1
Output: 0
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
```
## 第一次解法
````javascript
/**
* @param {number} num
* @return {number}
*/
var findComplement = function(num) {
let a = '';
num.toString(2).split("").forEach(function(item){
if(item === "1"){
a += "0"
}else{
a += "1"
}
})
return parseInt(a,2)
};
# runtime : 89 ms
