Submission #1120756

#	Time	Username	Problem	Language	Result	Execution time	Memory
1120756		HasanV11010238	Tracks in the Snow (BOI13_tracks)	C++17	75.94 / 100	2055 ms	1048576 KiB

tracks

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long long
#define INF 1000000000
vector<vector<vector<int>>> v;
int bfs(int n, int st){
    vector<int> di(n + 6, INF), us(n + 6, 0);
    deque<int> q;
    di[st] = 0;
    q.push_back(st);
    while (!q.empty()){
        int x = q.front();
        q.pop_front();
        if (us[x]) continue;
        us[x] = 1;
        for (auto el : v[x]){
            if (el[0] >= di.size()) return -1;
            if (di[el[0]] > di[x] + el[1]){
                di[el[0]] = di[x] + el[1];
                if (el[1] == 0){
                    q.push_front(el[0]);
                }
                else{
                    q.push_back(el[0]);
                }
            }
        }
    }
    int ans = 0;
    for (int i = 0; i < n; i++){
        if (di[i] == INF) continue;
        ans = max(ans, di[i]);
    }
    return ans;
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, m;
    cin>>n>>m;
    v.resize((n + 5) * (m + 5));
    vector<string> s(n);
    for (int i = 0; i < n; i++){
        cin>>s[i];
        for (int j = 0; j < m; j++){
            if (s[i][j] == '.') continue;
            int v1 = (i + 1) * m + j + 1;
            if (i != 0 && s[i - 1][j] != '.'){
                int v2 = i * m + j + 1;
                if (v.size() <= max(v1, v2)){
                    cout<<-1;
                    return 0;
                }
                int va;
                if (s[i][j] == s[i - 1][j]){
                    va = 0;
                }
                else{
                    va = 1;
                }
                v[v1].push_back({v2, va});
                v[v2].push_back({v1, va});
            }
            if (j != 0 && s[i][j - 1] != '.'){
                int v2 = (i + 1) * m + j;
                int va;
                if (v.size() <= max(v1, v2)){
                    cout<<-1;
                    return 0;
                }
                if (s[i][j] == s[i][j - 1]){
                    va = 0;
                }
                else{
                    va = 1;
                }
                v[v1].push_back({v2, va});
                v[v2].push_back({v1, va});
            }
        }
    }
    cout<<bfs((n + 1) * (m + 1), m + 1) + 1;
}

Compilation message (stderr)

tracks.cpp: In function 'int bfs(int, int)':
tracks.cpp:18:23: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |             if (el[0] >= di.size()) return -1;
tracks.cpp: In function 'int main()':
tracks.cpp:52:30: warning: comparison of integer expressions of different signedness: 'std::vector<std::vector<std::vector<int> > >::size_type' {aka 'long unsigned int'} and 'const int' [-Wsign-compare]
   52 |                 if (v.size() <= max(v1, v2)){
      |                     ~~~~~~~~~^~~~~~~~~~~~~~
tracks.cpp:69:30: warning: comparison of integer expressions of different signedness: 'std::vector<std::vector<std::vector<int> > >::size_type' {aka 'long unsigned int'} and 'const int' [-Wsign-compare]
   69 |                 if (v.size() <= max(v1, v2)){
      |                     ~~~~~~~~~^~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 45.9375 / 70