Submission #1278332

#	Time	Username	Problem	Language	Result	Execution time	Memory
1278332		hoa208	Mecho (IOI09_mecho)	C++20	100 / 100	281 ms	6772 KiB

mecho

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; i++)
#define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; i--)
#define pa pair<ll, ll>
#define fi first
#define se second
#define bit(mask, j) ((mask >> j) & 1)
const   ll mod = 1e9 + 7;
const   ll INF = 1e18;
//--------------------------------------------------------------------

void hbmt() {
    ll n, s;
    cin >> n >> s;
    pa M, D;
    vector<pa>  vbee;
    vector<vector<char>> a(n + 1, vector<char> (n + 1, ' '));
    vector<vector<ll>> mark(n + 1, vector<ll> (n + 1, 0));
    FOR(i, 1, n) {
        FOR(j, 1, n) {
            cin >> a[i][j];
            if(a[i][j] == 'M') {
                M = {i, j};
            }
            else if(a[i][j] == 'H') {
                vbee.push_back({i, j});
            }
            else if(a[i][j] == 'D') {
                D = {i, j};
            }
        }
    }
    pa mov[] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    auto outside = [&] (ll x, ll y) {
        return x <= 0 || x > n || y <= 0 || y > n;
    };
    auto check = [&] (ll x) {
        queue<pa> qbee;
        queue<pa> q;
        q.push(M);
        FOR(i, 1, n) FOR(j, 1, n) mark[i][j] = 0;
        mark[M.fi][M.se] = 1;
        for(auto e : vbee) {
            qbee.push(e);
            mark[e.fi][e.se] = -1;
        }
        while(x--) {
            ll t = qbee.size();
            while(t--) {
                pa u = qbee.front();
                qbee.pop();
                FOR(i, 0, 3) {
                    pa v = {mov[i].fi + u.fi, mov[i].se + u.se};
                    if(outside(v.fi, v.se) || a[v.fi][v.se] == 'T' || a[v.fi][v.se] == 'D') 
                        continue;
                    if(mark[v.fi][v.se] != -1) {
                        mark[v.fi][v.se] = -1;
                        qbee.push(v);
                    }
                }
            }
        }
        while(1) {
            ll _s = s;
            while(_s--) {
                ll t = q.size();
                while(t--) {
                    pa u = q.front();
                    q.pop();
                    if(mark[u.fi][u.se] == -1) continue;
                    FOR(i, 0, 3) {
                        pa v = {mov[i].fi + u.fi, mov[i].se + u.se};
                        if(outside(v.fi, v.se) || a[v.fi][v.se] == 'T') 
                            continue;
                        if(mark[v.fi][v.se] == 0) {
                            mark[v.fi][v.se] = 1;
                            q.push(v);
                        }
                    }
                }
            }
            if(mark[D.fi][D.se] == 1) return true;
            if(q.size() == 0) return false;
            ll t = qbee.size();
            while(t--) {
                pa u = qbee.front();
                qbee.pop();
                FOR(i, 0, 3) {
                    pa v = {mov[i].fi + u.fi, mov[i].se + u.se};
                    if(outside(v.fi, v.se) || a[v.fi][v.se] == 'T' || a[v.fi][v.se] == 'D') 
                        continue;
                    if(mark[v.fi][v.se] != -1) {
                        mark[v.fi][v.se] = -1;
                        qbee.push(v);
                    }
                }
            }
        }
        return false;
    };
    ll l = 0, r = n * n;
    ll res = -1;
    while(l <= r) {
        ll mid = l + r >> 1;
        if(check(mid)) {
            l = mid + 1;
            res = mid;
        }
        else r = mid - 1;
    }
    cout << res << '\n';
}

int main() {
    
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);

    #define NAME "hbmt"
    if(fopen(NAME".inp", "r")) {
        freopen(NAME".inp", "r", stdin);
        freopen(NAME".out", "w", stdout);
    }
    
    //int t;cin>>t;while(t--)
    hbmt();
    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:123:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  123 |         freopen(NAME".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:124:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  124 |         freopen(NAME".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100