两数之和

image-20210424211653362.png

  1. var twoSum = function(numbers, target) {
  2.     numbers.sort((a,b)=>{
  3.         return a<b?-1:1;
  4.     });
  5.     let len = numbers.length;
  6.     let left = 0;
  7.     let right = len-1;
  8.     while(left<right){
  9.         let sum = numbers[left] + numbers[right];
  10.         if(sum<target){
  11.             left++;
  12.         }else if(sum==target){
  13.             return [left+1,right+1];
  14.         }else{
  15.             right--;
  16.         }
  17.     }
  18.     return [-1,-1];
  19. };

翻转字符串

image-20210424214814704.png

var reverseString = function(s) {
    let len = s.length;
    let left = 0;
    let right = len - 1;
    while(left<right){
        swap(s,left,right);
        left++,right--;
    }
    return s;
};
let swap = function (s,left,right){
    // 另一种写法,JS特有的
    // [s[right],s[left]]=[s[left],s[right]];
    let temp = s[left];
    s[left] = s[right];
    s[right] = temp;
}