【LeetCode】解题1：Two Sum

Problem 1: Two Sum [Easy]

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, and you may not use the same element twice.

Example:

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

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

来源：LeetCode

Solution (Java)

class Solution {
    public int[] twoSum(int[] nums, int target) {
        int len = nums.length;
        for(int i = 0; i < len; i++){
            for(int j = i+1; j < len; j++){
                if(nums[i] + nums[j] == target){
                    return new int[] {i, j};
                }
            }
        }
        throw new IllegalArgumentException("No solution");
    }
}

修改过程

• 第一层循环只到len/2导致没有搜索到两个索引都在数组后半部分的结果。（写的时候脑抽？）
• 改进：比起在两层循环结束后返回结果，在搜索到结果之后直接return显得更为简洁。