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 same element twice.

Example:

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

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

return [0, 1].

算法复杂度O(nlogn)

public class Solution {    public int[] twoSum(int[] nums, int target) {        int[] p=new int[2];        for(int i=0;i

discuss里中O(n)方法

class Solution {    public int[] twoSum(int[] nums, int target) {        Map
    
      map = new HashMap
     
      ();        int[] res = new int[2];        int length = nums.length;        for(int i = 0; i< length;i++){            if(map.containsKey(nums[i])){                res[1]=i;                res[0]=map.get(nums[i]);            }else{                map.put(target-nums[i],i);            }        }    return res;    }}