LeetCode C++ two sum 兩數之和

今天要練習的 LeetCode 題目是 two sum 兩數之和，並且以 C++ 實作出來。

LeetCode 題目

https://leetcode.com/problems/two-sum/
難度：Easy

two sum 是 LeetCode 題目的第 1 題，
題目是給一個 nums 序列，而且由 nums 序列中的任兩個數字加起來會是 target 這個數字，
題目要求你找出這兩組數字的索引值。

答案

以下為 C++ two sum 的 solution

cpp-two-sum.cpp

// g++ cpp-two-sum.cpp -o a.out -std=c++11
#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        for(int i = 0; i < nums.size(); i++) {
            for(int j = i+1; j < nums.size(); j++) {
                if(nums[i]+nums[j] == target)
                    return vector<int>({i,j});
            }
        }
        return vector<int>();
    }
};

int main() {
    vector<int> nums = {2,7,11,15}; int target = 9; // [0,1]
    //vector<int> nums = {3,2,4}; int target = 6; // [1,2]
    //vector<int> nums = {3,3}; int target = 6; // [0,1]
    Solution s;
    vector<int> ret = s.twoSum(nums, target);
    cout << "[" << ret[0] << "," << ret[1] << "]\n";

    return 0;
}

參考
Two Sum - LeetCode
https://leetcode.com/problems/two-sum/
兩數之和 (Two Sum) - 力扣 (LeetCode)
https://leetcode-cn.com/classic/problems/two-sum/description/