LeetCode：Two Sum

　　最近看大牛的博客，有提到LeetCode-OJ，于是也上去凑个热闹。不定期更新我做的题。

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

　　一开始还以为输入是有序数组，就写了个先查找第一个不小于target一半的数，再在区间内进行二分查找的程序，提交不通过。发现错误后，就直接使用两重循环暴力破解法。

public class Solution {
    public int[] twoSum(int[] nums, int target) {
       if (nums == null){
            return null;
        }
        for(int i=0; i<nums.length; i++){
            //注意j=i+1
            for(int j=i+1; j<nums.length; j++){
                if(nums[i]+nums[j] == target){
                    return new int[]{i+1,j+1};
                }
            }
        }
        return null;
    }
}