leetcode [#1]

目录

• 1. 题目
• 2. 解决方案
• 3. 注意事项

题目

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

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

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

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

Note:
The return format had been changed to zero-based indices. Please read the above updated description carefully.

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解决方案

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

        int[] result = new int[2];

        for(int i = 0; i<N;i++){
            for(int j = i + 1;j<N;j++){
                if(nums[i] + nums[j] == target){
                    result[0] = i;
                    result[1] = j;
                    break;
                }
            }
        }
        return result;
    }
}

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注意事项

1. 两次循环遍历找到相应元素，属于暴力解法。
2. 更优的解法考虑使用HashMap