1. 两数之和

https://leetcode-cn.com/problems/3sum/

package 数组;

import java.util.Arrays;
import java.util.HashMap;

public class 两数之和 {

    public static void main(String[] args) {
        int[] nums = {3, 2, 4};
        两数之和 两数之和 = new 两数之和();
        int[] result = 两数之和.twoSum(nums, 6);
        System.out.println(Arrays.toString(result));
    }

    // 方法一：暴力循环：target减去遍历到的数，去数组找另一个数
    public int[] twoSum(int[] nums, int target) {
        int[] result = new int[2];
        if (nums == null || nums.length == 0) {
            return null;
        }
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            map.put(nums[i], i);
        }
        for (int i = 0; i < nums.length; i++) {
            int other = target - nums[i];
            if (map.containsKey(other) && map.get(other) != i) {
                result[0] = i;
                result[1] = map.get(other);
                return result;
            }
        }
        return null;
    }
}