LeetCode:1.两数之和

LeetCode:1.两数之和

新建一个字典作为婚姻介绍所。nums里的值，逐个来介绍所找对象，没有合适的就先登记着，有合适的就牵手成功。

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    let map=new Map()
    let diff
    let result=[]
    nums.forEach((item,index)=>{
        diff=target-item
        if(map.has(diff)){
            result=[index,map.get(diff)]
        }else{
            map.set(item,index)
        }
    })
    return result
};
//time 6ms 54mb  O(n)
// es6 api time fast

//for time 72ms 35mb

'

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    for(let i=0;i<nums.length;i++){
        for(let j=i+1;j<nums.length;j++){
            if(nums[i]+nums[j]==target){
                return [i,j]
            }
        }
    }
};



/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    let map=new Map()
    for(let i=0;i<nums.length;i++){
        if(map.get(target-nums[i])!=undefined){
            return [i,map.get(target-nums[i])]
        }else{
            map.set(nums[i],i)
        }
    }
};