제출 #491455

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
491455		XII	Mecho (IOI09_mecho)	C++17	100 / 100	169 ms	10704 KiB

mecho

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
#define ALL(x) (x).begin(), (x).end()

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORU(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)

#define IOS cin.tie(0)->sync_with_stdio(false);
#define PROB "IOI09_mecho"
void Fi(){
    if(fopen(PROB".inp", "r")){
        freopen(PROB".inp", "r", stdin);
        freopen(PROB".out", "w", stdout);
    }
}

const int INF = 1e9;
const int N = 800 + 1;
int n, spd;
int a[N][N];
using pi = pair<int, int>;
pi S, E;
queue<pi> qe;

int d[N][N];
const int dx[] = {0, 0, -1, +1};
const int dy[] = {-1, +1, 0, 0};

void bfsBee(){
    while(!qe.empty()){
        auto [x, y] = qe.front(); qe.pop();
        FOR(direc, 0, 4){
            int i = x + dx[direc];
            int j = y + dy[direc];
            if(i < 1 || n < i || j < 1 || n < j) continue;
            if(a[i][j] == 1 && d[i][j] == -1){
                d[i][j] = d[x][y] + 1;
                qe.emplace(i, j);
            }
        }
    }
}

pi D[N][N];
bool bfsMecho(const int &T){
    FORU(i, 1, n) FORU(j, 1, n) D[i][j] = {INF, INF};
    qe.emplace(S); D[S.fi][S.se] = {T, 0};
    while(!qe.empty()){
        auto [x, y] = qe.front(); qe.pop();
//        cout << x << " " << y << " " << D[x][y].fi << " " << D[x][y].se << "\n";
        FOR(direc, 0, 4){
            int i = x + dx[direc];
            int j = y + dy[direc];
            if(i < 1 || n < i || j < 1 || n < j) continue;
            if(a[i][j] && D[i][j].fi == INF){
                D[i][j] = D[x][y];
                if(++D[i][j].se >= spd){
                    ++D[i][j].fi;
                    D[i][j].se = 0;
                }
                if(a[i][j] == 2){
                    while(!qe.empty()) qe.pop();
                    return true;
                }
                if(D[i][j].fi < d[i][j]){
                    qe.emplace(i, j);
                }
            }
        }
    }
    return false;
}

int main(){
    IOS;
    Fi();
    cin >> n >> spd;
    memset(d, -1, sizeof(d));
    FORU(i, 1, n){
        string s; cin >> s;
        FORU(j, 1, n){
            switch(s[j - 1]){
                case 'T': a[i][j] = 0; break;
                case 'G': a[i][j] = 1; break;
                case 'M': a[i][j] = 1; S = {i, j}; break;
                case 'D': a[i][j] = 2; E = {i, j}; break;
                case 'H': a[i][j] = 0; qe.emplace(i, j); d[i][j] = 0; break;
            }
        }
    }
    bfsBee();
    int l = 0, r = d[S.fi][S.se] - 1, ans = -1;
    while(l <= r){
        int m = (l + r) / 2;
        if(bfsMecho(m)) l = m + 1, ans = m;
        else r = m - 1;
    }
    cout << ans;
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

mecho.cpp: In function 'void Fi()':
mecho.cpp:20:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen(PROB".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:21:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen(PROB".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100