1. Two Sum - LeetCode

LeetCode Problems Solutions

question description: 问题描述

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.
给定一个整型数组，数组内两个数相加得到一个特定的值，返回这两个数字的索引。
你可以假定每次输入都有一个确切的解决方案，同时、你不能两次使用同一个数字。

Example:例如

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

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

Thinking

基本排序算法中的选择排序是假定第0个为最小的，然后通过两次循环逐次比较(面试常见的基本排序算法)。我们也可以借助该思想，假定两个数中的第一个数是从第一个开始的，通过两次循环来获得两个数的索引。

solution with java - Java解决方案

public int[] twoSum(int[] nums, int target) {
        
        for (int i = 0; i < nums.length; i++){
            
            int first = nums[i];
            
            for ( int j = i + 1; j < nums.length ; j++){
                
                int secode = nums[j];
                
                if ( first + secode == target){

                    return new int[]{i,j};
                }
                
            }
              
        }
        
        return new int[]{0,0};
        
    }

solution with swift - swift解决方案

func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
        
        for i in 0 ..< nums.count  {
            
            let first = nums[i];
            
            for j in (i+1) ..< nums.count {
                
                let seconde = nums[j];
                
                if first + seconde == target {
                    
                    return [i,j];
                }
            }
            
        }
        return [0,0];
    }