Submission #518468

#TimeUsernameProblemLanguageResultExecution timeMemory
518468Alex_tz307Mecho (IOI09_mecho)C++17
10 / 100
188 ms6232 KiB
#include <bits/stdc++.h> #define INF 0x3f3f3f3f using namespace std; void testCase() { int n, s; cin >> n >> s; vector<string> a(n); queue<pair<int, int>> q; vector<vector<int>> bee(n, vector<int>(n, INF)); int istart = -1, jstart = -1, istop = -1, jstop = -1; for (int i = 0; i < n; ++i) { cin >> a[i]; for (int j = 0; j < n; ++j) { if (a[i][j] == 'H') { bee[i][j] = 1; q.emplace(i, j); } else if (a[i][j] == 'M') { istart = i, jstart = j; } else if (a[i][j] == 'D') { istop = i, jstop = j; } } } const int di[] = {-1, 0, 1, 0}, dj[] = {0, 1, 0, -1}; auto valid = [&](const int &i, const int &j) -> bool { return 0 <= min(i, j) && max(i, j) < n && a[i][j] != 'T' && a[i][j] != 'H'; }; while (!q.empty()) { int i, j; tie(i, j) = q.front(); q.pop(); for (int k = 0; k < 4; ++k) { int iv = i + di[k], jv = j + dj[k]; if (valid(iv, jv) && a[iv][jv] != 'D' && bee[iv][jv] == INF) { bee[iv][jv] = bee[i][j] + 1; q.emplace(iv, jv); } } } auto checkDistance = [&](const int &m, const int &b) -> bool { return m / s < b; }; auto check = [&](const int &t) -> bool { vector<vector<int>> dp(n, vector<int>(n, INF)); queue<pair<int, int>> q; dp[istart][jstart] = t; q.emplace(istart, jstart); while (!q.empty()) { int i, j; tie(i, j) = q.front(); q.pop(); for (int k = 0; k < 4; ++k) { int iv = i + di[k], jv = j + dj[k]; if (valid(iv, jv) && dp[iv][jv] == INF && checkDistance(dp[i][j] + 1, bee[iv][jv] - t)) { dp[iv][jv] = dp[i][j] + 1; q.emplace(iv, jv); } } } if (dp[istop][jstop] == INF) { return false; } return true; }; int l = 0, r = bee[istart][jstart] - 1, ans = -1; while (l <= r) { int mid = (l + r) / 2; if (check(mid)) { ans = mid; l = mid + 1; } else { r = mid - 1; } } cout << ans << '\n'; } int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int tests = 1; for (int tc = 0; tc < tests; ++tc) { testCase(); } return 0; }
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