Submission #991111

#	Time	Username	Problem	Language	Result	Execution time	Memory
991111		yellowtoad	Senior Postmen (BOI14_postmen)	C++17	100 / 100	230 ms	78984 KiB

postmen

#include <iostream>
#include <vector>
#define f first
#define s second
using namespace std;

int n, m, vis[500010], viss[500010];
vector<pair<int,int>> edge[500010];
vector<vector<int>> path;
vector<int> pth;

inline bool dfs(int u, int tar, int can) {
    pth.push_back(u);
    if ((u == tar) && (can)) {
        path.push_back(pth);
        return 1;
    }
    while ((edge[u].size()) && (vis[edge[u].back().s])) edge[u].pop_back();
    if (edge[u].empty()) return 0;
    vis[edge[u].back().s] = 1;
    return dfs(edge[u].back().f,tar,1);
}

inline void solve(int u) {
    pth.clear();
    if (!dfs(u,u,0)) return;
    int iter = path.size()-1;
    vector<int> stk;
    for (int i = 0; i < path[iter].size(); i++) {
        if (viss[path[iter][i]]) {
            cout << path[iter][i];
            while (stk.back() != path[iter][i]) {
                cout << " " << stk.back();
                viss[stk.back()] = 0;
                stk.pop_back();
            } cout << "\n";
        } else {
            viss[path[iter][i]] = 1;
            stk.push_back(path[iter][i]);
        }
    }
    for (int i = 0; i < path[iter].size(); i++) viss[path[iter][i]] = 0;
    for (int i = 0; i < path[iter].size()-1; i++) solve(path[iter][i]);
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        edge[u].push_back({v,i});
        edge[v].push_back({u,i});
    }
    solve(1);
}

Compilation message (stderr)

postmen.cpp: In function 'void solve(int)':
postmen.cpp:29:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for (int i = 0; i < path[iter].size(); i++) {
      |                     ~~^~~~~~~~~~~~~~~~~~~
postmen.cpp:42:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |     for (int i = 0; i < path[iter].size(); i++) viss[path[iter][i]] = 0;
      |                     ~~^~~~~~~~~~~~~~~~~~~
postmen.cpp:43:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for (int i = 0; i < path[iter].size()-1; i++) solve(path[iter][i]);
      |                     ~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 38 / 38
• Subtask 2: 17 / 17
• Subtask 3: 45 / 45