leetcode-1

题目：

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.

Example:

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

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



代码：
public int[] twoSum(int[] nums, int target) {
        
     int[] res = new int[2];
     HashMap<Integer, Integer> map = new HashMap();
     for(int i = 0; i< nums.length; i++){
     int valNeed = target - nums[i];
     if(map.get(nums[i]) != null){
     res[0] = map.get(nums[i]);
     res[1] = i;
     break;
     }
     map.put(valNeed, i);
     }
     return res;
    }