Two Sum

import java.util.HashMap;

public class TwoSum {

    public static void main(String[] args) {
        int[] sums = { 3, 2, 4 };
        int target = 6;
        int[] res = twoSum(sums, target);
        int[] indexs = getTwoIndexs(sums,target);
        for (int i = 0; i < res.length; i++) {
            System.out.println(res[i]);
        }
        for (int i = 0; i < indexs.length; i++) {
            System.out.println(indexs[i]);
        }
    }

    // HashMap的解决方式，参考了网上的，又学习了HashMap
    private static int[] getTwoIndexs(int[] nums, int target) {
        int[] twoIndexs = new int[2];
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        for (int i = 0; i < nums.length; i++) {
            if (map.containsKey(nums[i])) {
                int index = map.get(nums[i]);
                twoIndexs[0] = Math.min(i+1, index+1);
                twoIndexs[1] = Math.max(i+1, index+1);
                break;
            }
            int value = target - nums[i];
            map.put(value, i);
        }
        return twoIndexs;
    }

    // 之前自己写的解决方式，明显不好
    private static int[] twoSum(int[] nums, int target) {
        int[] res = new int[2];
        for (int i = 0; i < nums.length; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[i] + nums[j] == target) {
                    res[0] = i + 1;
                    res[1] = j + 1;
                }
            }
        }
        return res;
    }

}