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parent
3cc48c7648
commit
e7cdf0de45
2
Makefile
2
Makefile
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@ -1,4 +1,4 @@
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CXXFLAGS=-Wall -Wextra -std=c++11
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CXXFLAGS=-Wall -Wextra -std=c++11 -g
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SHELL=bash
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.PHONY: run
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#include <iostream>
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#include <queue>
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#include <tuple>
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using namespace std;
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using pos = tuple<long, long>;
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using node = tuple<long, long>;
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const auto MAX = static_cast<long>(1e10);
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int main()
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{
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long m, n, x; cin >> m >> n;
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vector<vector<node>> vault(m, vector<node>(n));
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vector<vector<bool>> seen(m, vector<bool>(n, false));
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for (long i = 0; i < m; ++i) {
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for (long j = 0; j < n; ++j) {
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cin >> x; vault[i][j] = make_tuple(x, MAX);
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}
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}
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auto neighbors = [m,n](pos p) {
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long i = get<0>(p), j = get<1>(p);
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vector<pos> ns; ns.reserve(4);
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if (i > 0) ns.push_back(make_tuple(i-1,j));
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if (i < m-1) ns.push_back(make_tuple(i+1,j));
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if (j > 0) ns.push_back(make_tuple(i,j-1));
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if (j < n-1) ns.push_back(make_tuple(i,j+1));
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return ns;
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};
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auto length = [&vault](pos a, pos b) {
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auto d = get<0>(vault[get<0>(b)][get<1>(b)]) - get<0>(vault[get<0>(a)][get<1>(a)]);
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return d <= 0 ? 0 : d;
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};
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priority_queue<tuple<long, pos>> q;
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q.push(make_tuple(0, make_tuple(0, 0))); get<1>(vault[0][0]) = 0;
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while (!q.empty()) {
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auto u = get<1>(q.top()); q.pop();
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long i = get<0>(u), j = get<1>(u);
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auto & vu = vault[i][j];
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// cerr << "(" << get<0>(u) << "," << get<1>(u) << ") " << endl;
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if (seen[i][j]) continue;
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for (auto & v : neighbors(u)) {
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auto & vv = vault[get<0>(v)][get<1>(v)];
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auto d = max(get<1>(vu), length(u, v));
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// cerr << "(" << get<0>(v) << "," << get<1>(v) << ") " << get<1>(vv) << " " << d << endl;
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if (d < get<1>(vv)) {
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get<1>(vv) = d; q.push(make_tuple(-d, v));
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}
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}
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seen[i][j] = true;
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}
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// for (long i = 0; i < m; ++i) {
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// for (long j = 0; j < n; ++j) {
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// cerr << get<1>(vault[i][j]) << " ";
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// }
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// cerr << endl;
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// }
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cout << get<1>(vault[m-1][n-1]) << endl;
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}
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