Contents

1. 1. 题目：

题目：

一个数组中两个位置上的数的和恰为 target，求这两个位置。

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

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

	return [0, 1].
	
public class TowSum {

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