Leetcode--1. Two Sum(easy)

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the sameelement twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

class Solution {
    public int[] twoSum(int[] nums, int target) {
        HashMap<Integer,Integer> mp=new HashMap<Integer,Integer>();
        int len=nums.length;
        for(int i=0;i<len;i++){
            if(mp.containsKey(nums[i])){
                int value=mp.get(nums[i]);
                return new int[]{value,i};
            }
            else{
                mp.put(target-nums[i],i);
            }
        }
        return new int[2];
    }
}