how to output the elements of a vector on one line?

[shinxg]

how to output the elements of a vector on one line?

 for(int i = 0; i < result.size(); i++)
    {
        std::cout<< result[i];
        std::cout.flush();
    }

why I can not see the number on my Mac?

[Moschops]

#include <vector>
#include <iostream>

using std::cout;
using std::endl;
using std::vector;

int main()
{
  vector<int> result;
  result.push_back(3);
  result.push_back(4);

  for(int i = 0; i < result.size(); i++)
    {
        std::cout<< result[i];
        std::cout.flush();
    }
}

That outputs

34

https://ideone.com/j6W2sF

Does it do if you build that code on your system?

If it does, then I'd guess that the problem is that your vector is empty.

[gunnerfunner]

One reason you may not be able to print on one line is if the type of elements held in the std::vector result already have a stream insertion operator overload defined with a newline character in it

[shinxg]

here is the code
//
// main.cpp
// TwoSum
//
// Created by shinxg on 2017/5/7.
// Copyright © 2017年 shinxg. All rights reserved.
//

//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].
#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
vector<int> result(2);
for (int i = 0; i < nums.size(); i++) {
for (int j = i + 1; j < nums.size(); j++) {
if(nums[i]+nums[j] == target)
{
result[0] = i;
result[1] = j;
return result;
}
}
}
return result;
}
};

//vector<int> twoSum(vector<int> &numbers, int target)
//{
// //Key is the number and value is its index in the vector.
// unordered_map<int, int> hash;
// vector<int> result;
// for (int i = 0; i < numbers.size(); i++) {
// int numberToFind = target - numbers[i];
//
// //if numberToFind is found in map, return them
// if (hash.find(numberToFind) != hash.end()) {
// //+1 because indices are NOT zero based
// result.push_back(hash[numberToFind] + 1);
// result.push_back(i + 1);
// return result;
// }
//
// //number was not found. Put it in the map.
// hash[numbers[i]] = i;
// }
// return result;
//}

int main(int argc, const char * argv[]) {
// insert code here...
std::vector<int> nums = {2, 7, 11, 15};
int target = 9;
std::vector<int> result(2);
Solution solution;
std::cout << "test" << std::flush;
result = solution.twoSum(nums, target);
std::cout << result.size() << std::endl;
std::cout << nums[2] << std::endl;
for(int i = 0; i < result.size(); i++)
{
std::cout<< result[i] << std::flush;
}
}

[gunnerfunner]

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

These restrictions have to be borne in mind and also a single function can replace class Solution:

#include <iostream>
#include <vector>
#include <iterator>

std::vector<size_t> twoSum(const std::vector<int>& nums, const int target)
{
    std::vector<size_t> result(2, 0);
    bool match = false;
    for (auto itr_trail = nums.cbegin(); itr_trail != nums.cend(); ++itr_trail)
    {
        for (auto itr_lead = itr_trail + 1; itr_lead != nums.cend(); ++itr_lead)
        {
            if( (*itr_lead) != (*itr_trail))
            //you may not use the same element twice
            {
                if((*itr_lead) + (*itr_trail) == target)
                {
                    result[0] = std::distance(nums.cbegin(), itr_trail);
                    //search if unfamiliar
                    result[1] = std::distance(nums.cbegin(), itr_lead);
                    match = true;
                    break;
                    //assume each input has exactly one solution ...
                    // ... so we can break after finding one solution
                }
            }
        }
        if (!match)std::cout << "No match found \n";
        return result;//[0,0] (i.e. no match) only case when both elements are same
    }
}

int main()
{
    std::vector<int> nums {2, 7, 11, 15};
    int target = 9;
    for (const auto& elem : twoSum(nums, target))std::cout << elem << " ";
}