Submission #836739

#	Time	Username	Problem	Language	Result	Execution time	Memory
836739		vgoofficial	Mecho (IOI09_mecho)	C++14	100 / 100	192 ms	8812 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<vector<bool>> maps;
vector<vector<int>> distBees;
int n,s;
pair<int, int> home, start;
vector<int> dx = {0,0,1,-1}, dy = {1,-1,0,0};
struct Compare {
	bool operator()(tuple<int, int, int> a, tuple<int, int, int> b) {
		return get<2>(a)>get<2>(b);
	}
};
void print(vector<vector<int>> v) {
    for(int i = 0; i < v.size(); i++) {
        for(int j = 0; j < v.size(); j++) {
            cout << v[i][j] << " ";
        }
        cout << endl;
    }
    cout << endl;
}
bool possible(int mid) {
    vector<vector<int>> temp = distBees;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) temp[i][j]-=mid;
    }
    //cout << mid << endl;
    //print(temp);
    vector<vector<int>> minDist(n, vector<int>(n, 1000000000));
    minDist[start.first][start.second]=0;
    deque<pair<int, int>> q;
    q.push_back(start);
    while(q.size()) {
        pair<int, int> p = q.front();
        q.pop_front();
        for(int i = 0; i < 4; i++) {
            int newx = p.first+dx[i], newy = p.second+dy[i];
            if(newx>=0&&newy>=0&&newx<n&&newy<n&&maps[newx][newy]&&minDist[newx][newy]==1000000000) {
                if((minDist[p.first][p.second]+1)/s<=temp[newx][newy]) {
                    minDist[newx][newy]=minDist[p.first][p.second]+1;
                    q.push_back({newx, newy});
                }
            }
        }
    }

    return minDist[home.first][home.second]!=1000000000;
}
int main() {
    ios_base::sync_with_stdio(false); 
    cin.tie(0);
    cin >> n >> s;
    deque<pair<int, int>> bee;
    maps=vector<vector<bool>>(n, vector<bool>(n));
    distBees=vector<vector<int>>(n, vector<int>(n, 1000000000));
    for(int i = 0; i < n; i++) {
        string t;
        cin >> t;
        for(int j = 0; j < n; j++) {
            if(t[j]=='G') {
                maps[i][j]=true;
            } else if(t[j]=='M') {
                start={i,j};
                maps[i][j]=true;
            } else if(t[j]=='D') {
                home = {i,j};
            } else if(t[j]=='H') {
                bee.push_back({i,j});
                distBees[i][j]=-1;
            }
        }
    }
    while(bee.size()) {
        pair<int, int> p = bee.front();
        bee.pop_front();
        for(int i = 0; i < 4; i++) {
            int newx = p.first+dx[i], newy = p.second+dy[i];
            if(newx>=0&&newy>=0&&newx<n&&newy<n&&maps[newx][newy]&&distBees[newx][newy]==1000000000) {
                distBees[newx][newy]=distBees[p.first][p.second]+1;
                bee.push_back({newx, newy});
            }
        }
    }
    maps[home.first][home.second]=true;
    //print(distBees);
    int lo = 0, hi = distBees[start.first][start.second];
    if(!possible(0)) {
        cout << -1 << endl;
        return 0;
    }
    while(lo+1<hi) {
        int mid = (lo+hi)/2;
        if(possible(mid)) {
            lo=mid;
        } else {
            hi=mid;
        }
    }
    if(possible(hi)) {
        cout << hi << endl;
    } else {
        cout << lo << endl;
    }
}

Compilation message (stderr)

mecho.cpp: In function 'void print(std::vector<std::vector<int> >)':
mecho.cpp:15:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     for(int i = 0; i < v.size(); i++) {
      |                    ~~^~~~~~~~~~
mecho.cpp:16:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |         for(int j = 0; j < v.size(); j++) {
      |                        ~~^~~~~~~~~~

• Subtask 1: 100 / 100