1. 两数之和 - 力扣（Leetcode）

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
import java.util.Scanner;
import java.util.HashMap;
import java.util.Map;


//两数之和1
public class TwoSum1 {
	public static void main(String[] args){
		Scanner input = new Scanner(System.in);

		int[] nums = {9,1,3,5,34};
		
		System.out.print("nums:");
		for (int i : nums) {
			System.out.print("\t" + i);
		}
		boolean again = true;
		while(again){
			System.out.print("\n请输入 target(666 退出)：");
			int inputNum = input.nextInt();

			if (inputNum == 666) {
				break;
			}

			int[] res = new Solution().twoSum(nums,inputNum);
			if (res != null) {
				System.out.println("\n nums[" + res[0] + "] + nums[" + res[1] + "] = " + inputNum);
			}else{
				System.out.println("匹配失败。");
			}
		}
		
	}
}

class Solution {
    public int[] twoSum(int[] nums, int target) {
    	
    	if (nums == null || nums.length == 0) {
    		return null;
    	}

    	Map<Integer,Integer> map = new HashMap<>();

    	for(int i = 0; i < nums.length; i++){
    		int temp = target - nums[i];
    		if (map.containsKey(temp)) {
    			int[] res = new int[2];
    			res[1] = i;
    			res[0] = map.get(temp);
    			return res;
    		}
    		map.put(nums[i],i);
    	}
    	return null;
    }
}