HackerRank : Dijkstra: Shortest Reach 2 (c++)

HackerRank링크

https://www.hackerrank.com/challenges/dijkstrashortreach/problem

Dijkstra: Shortest Reach 2 | HackerRank

코드 풀이

일반적인 다익스트라 풀이였다.

• 결과를 저장할 Result벡터, 각 노드간 최종 거리를 저장할 Dist벡터, Graph를 새로 저장하기위한 벡터 선언
• 다익스트라를 실행하기위한 우선순위큐 선언
• 초기값 push
• Graph 새로 연결
• 기본적인 다익스트라 코드 구현
• 최종적인 결과값들 Result로 push_back

코드

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

/*
 * Complete the 'shortestReach' function below.
 *
 * The function is expected to return an INTEGER_ARRAY.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. 2D_INTEGER_ARRAY edges
 *  3. INTEGER s
 */
 #define INF 2000000000
 

vector<int> shortestReach(int n, vector<vector<int>> edges, int s) 
{
    vector<int> Result;
    vector<int> vecDist(n + 1, INF);
    vector<pair<int, int>> Graph[3001];
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    pq.push({0, s});
    vecDist[s] = 0;
    
    for(int i = 0; i < edges.size(); ++i)
    {
        int NodeA = edges[i][0];
        int NodeB = edges[i][1];
        int Cost = edges[i][2];
        Graph[NodeA].push_back({NodeB, Cost});
        Graph[NodeB].push_back({NodeA, Cost});
    }
    
    while(!pq.empty())
    {
        int CurNode = pq.top().second;
        int CurCost = pq.top().first;
        pq.pop();
        
        if(vecDist[CurNode] < CurCost)
        {
            continue;
        }
        size_t Size = Graph[CurNode].size();
        for(size_t i = 0; i < Size; ++i)
        {
            int NextCost = Graph[CurNode][i].second + CurCost;
            int NextNode = Graph[CurNode][i].first;
            
            if(vecDist[NextNode] > NextCost)
            {
                pq.push({NextCost, NextNode});
                vecDist[NextNode] = NextCost;
            }
        }
    }
    
    for(int i = 1; i < vecDist.size(); ++i)
    {
        if(i == s)
            continue;
        
        int Value = vecDist[i] == INF ? -1 : vecDist[i];
        
        Result.push_back((Value));
    }
    
    return Result;
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string t_temp;
    getline(cin, t_temp);

    int t = stoi(ltrim(rtrim(t_temp)));

    for (int t_itr = 0; t_itr < t; t_itr++) {
        string first_multiple_input_temp;
        getline(cin, first_multiple_input_temp);

        vector<string> first_multiple_input = split(rtrim(first_multiple_input_temp));

        int n = stoi(first_multiple_input[0]);

        int m = stoi(first_multiple_input[1]);

        vector<vector<int>> edges(m);

        for (int i = 0; i < m; i++) {
            edges[i].resize(3);

            string edges_row_temp_temp;
            getline(cin, edges_row_temp_temp);

            vector<string> edges_row_temp = split(rtrim(edges_row_temp_temp));

            for (int j = 0; j < 3; j++) {
                int edges_row_item = stoi(edges_row_temp[j]);

                edges[i][j] = edges_row_item;
            }
        }

        string s_temp;
        getline(cin, s_temp);

        int s = stoi(ltrim(rtrim(s_temp)));

        vector<int> result = shortestReach(n, edges, s);

        for (size_t i = 0; i < result.size(); i++) {
            fout << result[i];

            if (i != result.size() - 1) {
                fout << " ";
            }
        }

        fout << "\n";
    }

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}