CODEWITHSUNDEEP
c++
Davis Owen
Davis Owen

Reputation: 67

How to pass array of vector of pairs to function in c++

I am doing a hackerrank challenge called gridland metro and I have been toiling away at this for hours with no success. Basically I have looked at the editors solution and compared to my code and figured that the only substantial difference between our code is that the accepted solution does not pass this array "track" to a function, which I do. Here's the code.

#include <bits/stdc++.h>

using namespace std;

int gridlandMetro(int n, int m, int k, map<int,int> mp, vector< pair<int,int> > track) {
    long long total, non_emp, temp;
    int sz1,sz2;
    sz1 = mp.size();
    for(int i=0;i<sz1;i++){
        sort(track[i].begin(),track[i].end());
    }
    total = (long long)n*(long long)m;
    non_emp = 0;
    for(int i=0,p;i<sz1;i++){
        p = 0;
        sz2 = track[i].size();
        for(int j=0;j<sz2;j++){
            if(track[i][j].first <= p){
                temp = track[i][j].second - p;
                if(temp>0){
                    non_emp += temp;
                }
            }else{
                non_emp += (track[i][j].second - track[i][j].first + 1);
            }
            p = max(p,track[i][j].second);
        }
    }
    return total-non_emp;
}

vector< pair<int,int> > track[1003];
map<int,int>mp;

int main() {
    int n,m,k,r,c1,c2;
    cin >> n >> m >> k;
    for(int track_i = 0;track_i < k;track_i++){
        cin >> r >> c1 >> c2;
        if(mp.find(r) == mp.end()){
            mp[r] = mp.size();
        }
        r = mp[r];
        track[r].push_back(make_pair(c1,c2));
    }
    int result = gridlandMetro(n, m, k, mp, track);
    cout << result << endl;
    return 0;
}

It works on low inputs, but on large inputs it fails. I have tried passing the vector as a pointer, which seems to be what people suggest when passing arrays to functions. However this hasn't worked. I'll put the description of the challenge here but I don't think it's totally necessary.

The city of Gridland is represented as an matrix where the rows are numbered from to and the columns are numbered from to .

Gridland has a network of train tracks that always run in straight horizontal lines along a row. In other words, the start and end points of a train track are and , where represents the row number, represents the starting column, and represents the ending column of the train track.

The mayor of Gridland is surveying the city to determine the number of locations where lampposts can be placed. A lamppost can be placed in any cell that is not occupied by a train track.

Given a map of Gridland and its train tracks, find and print the number of cells where the mayor can place lampposts.

Note: A train track may (or may not) overlap other train tracks within the same row.

Input Format

The first line contains three space-separated integers describing the respective values of (the number of rows), (the number of columns), and (the number of train tracks). Each line of the subsequent lines contains three space-separated integers describing the respective values of , , and that define a train track.

Constraints

Output Format

Print a single integer denoting the number of cells where the mayor can install lampposts.

Upvotes: 1

Views: 1756

Answers (2)

Davis Owen
Davis Owen

Reputation: 67

So I'm stupid and it was just because my function was returning int instead of long long. Woops

Upvotes: 0

super
super

Reputation: 12928

You are using std::vector, std::pair and std::map already, so why not std::array aswell.

#include <array>

array<vector< pair<int,int> >, 1003> track;

int gridlandMetro(int n, int m, int k, map<int,int> mp, array<vector< pair<int,int> >, 1003>& track) {
    //...
}

Upvotes: 2

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