Find two numbers in the list so the sum can match the target number.

Solution

1. 最简单的brute force可以O（N^2)解决
   2.使用Hash Table直接做查询

class Solution {
    public int[] twoSum(int[] nums, int target) {
           Map<Integer,Integer> map = new HashMap<>();
            for(int i=0;i<nums.length;i++){
                int other=target - nums[i];
                if(map.containsKey(other))
                    return new int[] {map.get(other),i};
                
                map.put(nums[i],i);
            }
         throw new IllegalArgumentException("No two sum solution");
    }
}```