两和|| DSA || JavaScript ||作者：穆尼塞卡·乌达瓦拉帕蒂

Example 1:
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].
Example 2:
Input: nums = [3,2,4], target = 6
Output: [1,2]
Example 3:
Input: nums = [3,3], target = 6
Output: [0,1]

Constraints:
2 <= nums.length <= 104
-109 <= nums[i] <= 109
-109 <= target <= 109
Only one valid answer exists.

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]
            }
        }
    }
};

var twoSum = function(nums, target) {
    let map=new Map();
    for(let i=0;i<nums.length;i++){
        let v1=nums[i];
        let v2=target-v1;
        if(map.has(v2)){
            return [i,map.get(v2)]
        }
        map.set(v1,i)
    }
};