[leetcode 알고리즘] Two Sum - 난이도 Easy

 

1. Two Sum - 난이도 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].

 

 

 

 

내가 작성한 소스코드:

class Solution {
    
    public int[] twoSum(int[] nums, int target) {
        for(int i=0; i<nums.length; i++){
            for(int j=0; j<nums.length; j++){
                if(nums[i]+nums[j]==target){
                    return new int[] {i, j};
                }
            }
        }
        return null;
    }
}

 

 

Your input	[2,7,11,15] 9
Output	[0,1]
Expected	[0,1]

 

 

 

leetcode's solution:

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

 

 

솔루션 적용 후 전체 소스코드:

import java.util.Arrays;

class Solution {

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

public class Algo01 {
    public static void main(String[] args){
        Solution solution = new Solution();
        int[] nums = {2, 7, 11, 15};
        int target = 1;
        int[] result = solution.twoSum(nums, target);
        System.out.println(Arrays.toString(result));
    }
}