Submission #861179

#	Time	Username	Problem	Language	Result	Execution time	Memory
861179		qwusha	Portals (BOI14_portals)	C++17	70 / 100	351 ms	262144 KiB

portals

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first
#define se second
typedef long double ld;
const ll inf = 1e9;
const ld eps = 1e-8;



signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m;
    cin >> n >> m;
    int stai, staj, fini, finj;
    vector<vector<char>> a(n, vector<char>(m));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
            if (a[i][j] == 'S') {
                stai = i;
                staj = j;
            } else if (a[i][j] == 'C') {
                fini = i;
                finj = j;
            }
        }
    }
    vector<vector<vector<vector<int>>>> g(n, vector<vector<vector<int>>>(m));
    vector<vector<vector<pair<int, int>>>> steni(n, vector<vector<pair<int, int>>>(m));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == '#')
                continue;
            for (int c = 0; c < 4; c++) {
                int ci = (c % 2 == 0) * (c - 1),
                cj = (c % 2 == 1) * (c - 2);
                if (i + ci >= 0 && i + ci < n && j + cj >= 0 && j + cj < m && a[i + ci][j + cj] != '#') {
                    g[i][j].push_back({i + ci, j + cj, 1});
                }
            }
        }
    }
    for (int i = 0; i < n; i++) {
        pair<int, int> cur = {i, 0};
        for (int j = 0; j < m; j++) {
            if (a[i][j] == '#')
                cur = {i, j + 1};
            else
                steni[i][j].push_back(cur);
        }
        cur = {i, m - 1};
        for (int j = m - 1; j >= 0; j--) {
            if (a[i][j] == '#')
                cur = {i, j - 1};
            else
                steni[i][j].push_back(cur);
        }
    }
    for (int j = 0; j < m; j++) {
        pair<int, int> cur = {0, j};
        for (int i = 0; i < n; i++) {
            if (a[i][j] == '#')
                cur = {i + 1, j};
            else
                steni[i][j].push_back(cur);
        }
        cur = {n - 1, j};
        for (int i = n - 1; i >= 0; i--) {
            if (a[i][j] == '#')
                cur = {i - 1, j};
            else
                steni[i][j].push_back(cur);
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (i == 0 && j == 4) {
                int x = 1;
            }
            int mst = inf;
            int inde = -1;
            for (int qw = 0; qw < steni[i][j].size(); qw++) {
                auto [si, sj] = steni[i][j][qw];
                if (abs(si - i) + abs(sj - j) < mst) {
                    mst = abs(si - i) + abs(sj - j);
                    inde = qw;
                }
            }
            for (int qw = 0; qw < steni[i][j].size(); qw++) {
                auto [si, sj] = steni[i][j][qw];
                if (qw != inde && abs(si - i) + abs(sj - j) > mst + 1) {
                    g[i][j].push_back({si, sj, mst + 1});
                }
            }
        }
    }
    vector<vector<pair<int, int>>> par(n, vector<pair<int, int>>(m, {-1, -1}));
    vector<vector<int>> dist(n, vector<int>(m, inf));
    dist[stai][staj] = 0;
    set<vector<int>> st = {{0, stai, staj}};
    while (!st.empty()) {
        auto t = st.begin();
        auto qw = *t;
        int d = qw[0], vi = qw[1], vj = qw[2];
        st.erase(t);
        for (auto vec : g[vi][vj]) {
            int ui = vec[0], uj = vec[1], w = vec[2];
            if (d + w < dist[ui][uj]) {
                par[ui][uj] = {vi, vj};
                st.erase({dist[ui][uj], ui, uj});
                dist[ui][uj] = d + w;
                st.insert({d + w, ui, uj});
            }
        }
    }
    cout << dist[fini][finj] << '\n';
}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:81:21: warning: unused variable 'x' [-Wunused-variable]
   81 |                 int x = 1;
      |                     ^
portals.cpp:85:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |             for (int qw = 0; qw < steni[i][j].size(); qw++) {
      |                              ~~~^~~~~~~~~~~~~~~~~~~~
portals.cpp:92:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |             for (int qw = 0; qw < steni[i][j].size(); qw++) {
      |                              ~~~^~~~~~~~~~~~~~~~~~~~
portals.cpp:119:28: warning: 'finj' may be used uninitialized in this function [-Wmaybe-uninitialized]
  119 |     cout << dist[fini][finj] << '\n';
      |                            ^
portals.cpp:119:22: warning: 'fini' may be used uninitialized in this function [-Wmaybe-uninitialized]
  119 |     cout << dist[fini][finj] << '\n';
      |                      ^
portals.cpp:102:20: warning: 'staj' may be used uninitialized in this function [-Wmaybe-uninitialized]
  102 |     dist[stai][staj] = 0;
      |                    ^
portals.cpp:102:14: warning: 'stai' may be used uninitialized in this function [-Wmaybe-uninitialized]
  102 |     dist[stai][staj] = 0;
      |              ^

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30