LeetCode 之Two Sum

问题要求

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].
解题思路：考虑使用hashmap，将答案存于一个二维数组当中，遍历数组，将数组中的每个值与他对应的下标存储在hashmap中，直至找到一个数与前面的某一个数的和为target，找到这两个数对应的下标，存在二维数组当中。

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