Submission #446609

#	Time	Username	Problem	Language	Result	Execution time	Memory
446609		JerryLiu06	Mecho (IOI09_mecho)	C++17	100 / 100	200 ms	6424 KiB

mecho

#include <bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
using ld = long double;
using db = double;
using str = string;
 
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
 
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
 
#define mp make_pair
#define f first
#define s second
 
#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert 
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
 
#define lb lower_bound
#define ub upper_bound
 
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)
 
ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); }
ll fdiv(ll a, ll b) { return a / b - ((a ^ b) < 0 && a % b); }
 
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
 
template<class T> void remDup(vector<T>& v) { sor(v); v.erase(unique(all(v)), v.end()); }
 
const int MOD = 1e9 + 7;
const int MX = 810;
const ll INF = 1e18;

const int DIR[4][2] = { {1, 0}, {0, 1}, {-1, 0}, {0, -1} };

int N, S; char G[MX][MX]; int SX, SY, EX, EY;

int distToHive[MX][MX], distToStart[MX][MX];

bool valid(int X, int Y) { return X >= 1 && X <= N && Y >= 1 && Y <= N; }

bool valid(int tim) {
    memset(distToStart, -1, sizeof distToStart);

    distToStart[SX][SY] = 0; 

    queue<pi> Q; Q.push({SX, SY});

    while (!Q.empty()) {
        pi cur = Q.front(); Q.pop();
        
        if (distToHive[cur.f][cur.s] != -1 && distToStart[cur.f][cur.s] / S + tim >= distToHive[cur.f][cur.s]) {
            continue;
        }

        if (cur.f == EX && cur.s == EY) return true;

        F0R(i, 4) {
            int nx = cur.f + DIR[i][0];
            int ny = cur.s + DIR[i][1];

            if (!valid(nx, ny)) continue;

            if (G[nx][ny] != 'T' && distToStart[nx][ny] == -1) {
                distToStart[nx][ny] = distToStart[cur.f][cur.s] + 1;

                Q.push({nx, ny});
            }
        }
    }
    return false;
}

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

    cin >> N >> S; queue<pi> Q; memset(distToHive, -1, sizeof distToHive);
    
    FOR(i, 1, N + 1) FOR(j, 1, N + 1) {
        char C; cin >> C; if (C == 'M') { SX = i, SY = j; } if (C == 'D') { EX = i, EY = j; }

        if (C == 'H') { Q.push({i, j}); distToHive[i][j] = 0; } G[i][j] = C;
    }
    while (!Q.empty()) {
        pi cur = Q.front(); Q.pop();

        F0R(i, 4) {
            int nx = cur.f + DIR[i][0];
            int ny = cur.s + DIR[i][1];

            if (!valid(nx, ny)) continue; 

            if (distToHive[nx][ny] == -1 && G[nx][ny] != 'T' && G[nx][ny] != 'D') {
                distToHive[nx][ny] = distToHive[cur.f][cur.s] + 1;
                
                Q.push({nx, ny});
            }
        }
    }
    int low = 0; int high = N * N; int res = -1;

    while (low <= high) {
        int mid = (low + high) / 2;

        if (valid(mid)) {
            low = mid + 1; res = mid;
        }
        else {
            high = mid - 1;
        }
    }
    cout << res;
}

• Subtask 1: 100 / 100