Submission #966228

#	Time	Username	Problem	Language	Result	Execution time	Memory
966228		Pring	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	313 ms	130208 KiB

tracks

#include <bits/stdc++.h>
#pragma GCC optimize("O3","unroll-loops")
#pragma GCC target("avx2","popcnt","sse4","abm")
using namespace std;

#ifdef MIKU
string dbmc = "\033[1;38;2;57;197;187m", dbrs = "\033[0m";
#define debug(x...) cout << dbmc << "[" << #x << "]: ", dout(x)
void dout() { cout << dbrs << endl; }
template <typename T, typename ...U>
void dout(T t, U ...u) { cout << t << (sizeof...(u) ? ", " : ""); dout(u...); }
#else
#define debug(...) 39
#endif

#define fs first
#define sc second
#define mp make_pair
#define FOR(i, j, k) for (int i = j, Z = k; i < Z; i++)
using ll = long long;
typedef pair<int, int> pii;

const int MXN = 4005;
int n, m;
string s[MXN];
int dis[MXN][MXN];

void BFS(int srx, int sry) {
    deque<pii> dq;
    FOR(i, 0, n + 2) FOR(j, 0, m + 2) dis[i][j] = -1;
    auto PUSH = [&](int x, int y, int dx, int dy) -> void {
        dx += x;
        dy += y;
        if (s[dx][dy] == '.') return;
        if (dis[dx][dy] != -1) return;
        if (s[x][y] == s[dx][dy]) {
            dis[dx][dy] = dis[x][y];
            dq.push_front(mp(dx, dy));
        } else {
            dis[dx][dy] = dis[x][y] + 1;
            dq.push_back(mp(dx, dy));
        }
    };
    dis[srx][sry] = 1;
    dq.push_back(mp(srx, sry));
    while (dq.size()) {
        auto [x, y] = dq.front();
        dq.pop_front();
        PUSH(x, y, 1, 0);
        PUSH(x, y, -1, 0);
        PUSH(x, y, 0, 1);
        PUSH(x, y, 0, -1);
    }
}

void miku() {
    cin >> n >> m;
    FOR(i, 1, n + 1) {
        cin >> s[i];
        s[i] = '.' + s[i] + '.';
    }
    s[0] = string(m + 2, '.');
    s[n + 1] = string(m + 2, '.');
    BFS(1, 1);
    int ans = 0;
    FOR(i, 1, n + 1) FOR(j, 1, m + 1) {
        if (s[i][j] == '.') continue;
        ans = max(ans, dis[i][j]);
    }
    cout << ans << '\n';
}

int32_t main() {
    cin.tie(0) -> sync_with_stdio(false);
    cin.exceptions(cin.failbit);
    miku();
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70