Submission #1310995

#	Time	Username	Problem	Language	Result	Execution time	Memory
1310995		s101g	Mecho (IOI09_mecho)	C++20	76 / 100	139 ms	27436 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int inf = 1e9;
vector<int> dr{-1, 1, 0, 0}, dc{0, 0, 1, -1};
int n, s, mid;
vector<vector<char>> a;
int x, y, xx, yy;
vector<vector<int>> dis, diss;
bool vis[801][801] = {false};
void dfs(int r, int c)
{
    vis[r][c] = true;
    for (int i = 0; i < 4; i++)
    {
        int nr = r + dr[i], nc = c + dc[i];
        if (nr < 0 || nc < 0 || nr >= n || nc >= n || vis[nr][nc] || a[nr][nc] == 'T' || (dis[nr][nc] / s >= diss[nr][nc] - mid))
            continue;
        dfs(nr, nc);
    }
}
bool check()
{
    memset(vis, false, sizeof(vis));
    if (mid >= diss[x][y])
        return false;
    dfs(x, y);
    return vis[xx][yy];
}
int main()
{
    cin >> n >> s;
    a = vector<vector<char>>(n, vector<char>(n));
    queue<pair<int, int>> node;
    dis = vector<vector<int>>(n, vector<int>(n, inf));
    diss = vector<vector<int>>(n, vector<int>(n, inf));
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            cin >> a[i][j];
            if (a[i][j] == 'M')
            {
                x = i, y = j;
            }
            else if (a[i][j] == 'D')
            {
                xx = i, yy = j;
            }
            else if (a[i][j] == 'H')
            {
                node.push({i, j});
                diss[i][j] = 0;
            }
        }
    }
    while (!node.empty())
    {
        auto cur = node.front();
        node.pop();
        int r = cur.first, c = cur.second;
        for (int i = 0; i < 4; i++)
        {
            int nr = r + dr[i], nc = c + dc[i];
            if (nr < 0 || nr >= n || nc >= n || nc < 0 || a[nr][nc] == 'T' || a[nr][nc] == 'D')
                continue;
            if (diss[nr][nc] > diss[r][c] + 1)
            {
                diss[nr][nc] = diss[r][c] + 1;
                node.push({nr, nc});
            }
        }
    }
    node.push({x, y});
    dis[x][y] = 0;
    while (!node.empty())
    {
        auto cur = node.front();
        node.pop();
        int r = cur.first, c = cur.second;
        for (int i = 0; i < 4; i++)
        {
            int nr = r + dr[i], nc = c + dc[i];
            if (nr < 0 || nc < 0 || nr >= n || nc >= n || a[nr][nc] == 'T')
                continue;
            if (dis[nr][nc] > dis[r][c] + 1)
            {
                dis[nr][nc] = dis[r][c] + 1;
                node.push({nr, nc});
            }
        }
    }
    int l = -1, r = 2 * n * n;
    while (r > l + 1)
    {
        mid = (l + r) / 2;
        if (check())
            l = mid;
        else
            r = mid;
    }
    cout << l;
    return 0;
}

• Subtask 1: 76 / 100