Submission #769502

#	Time	Username	Problem	Language	Result	Execution time	Memory
769502		Ellinor	Tracks in the Snow (BOI13_tracks)	C++14	75.94 / 100	2089 ms	217932 KiB

tracks

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

#define rep(i,a,b) for(int i = (a); i < (b); i++)
typedef long long ll;

int H, W;
vector<string> grid;

vector<vector<bool>> visited; // bitset ?
vector<vector<ll>> dp;

priority_queue<vector<ll>> q;

void dfs(int hat, int wat, ll num)
{
    //cerr << hat << " " << wat << " " << num << "\n";

    if (visited[hat][wat]) return;
    if (grid[hat][wat] == '.') return;
    visited[hat][wat] = true;

    dp[hat][wat] = num;

    char ch = grid[hat][wat];
    if (hat + 1 < H) if (grid[hat + 1][wat] == ch) q.push({-num, hat + 1, wat});
    if (wat + 1 < W) if (grid[hat][wat + 1] == ch) q.push({-num, hat, wat + 1});
    if (hat - 1 >= 0) if (grid[hat - 1][wat] == ch) q.push({-num, hat - 1, wat});
    if (wat - 1 >= 0) if (grid[hat][wat - 1] == ch) q.push({-num, hat, wat - 1});

    if (hat + 1 < H) if (grid[hat + 1][wat] != ch) q.push({-(num + 1), hat + 1, wat});
    if (wat + 1 < W) if (grid[hat][wat + 1] != ch) q.push({-(num + 1), hat, wat + 1});
    if (hat - 1 >= 0) if (grid[hat - 1][wat] != ch) q.push({-(num + 1), hat - 1, wat});
    if (wat - 1 >= 0) if (grid[hat][wat - 1] != ch) q.push({-(num + 1), hat, wat - 1});
}

int32_t main()
{
    cin>>H>>W;
    grid.assign(H, "");
    rep(i,0,H){
        cin>>grid[i];
    }

    visited.assign(H, vector<bool>(W, false));
    dp.assign(H, vector<ll>(W, 0));
    q.push({-1,0,0});
    while(!q.empty())
    {
        auto x = q.top();
        q.pop();
        dfs(x[1], x[2], -(x[0]));
    }

    ll ans = 1;
    rep(i,0,H){
        rep(j,0,W){
            ans = max(ans, dp[i][j]);
            //cerr << dp[i][j]<< " ";
        }
        //cerr << "\n";
    }

    cout << ans;
}

• Subtask 1: 30 / 30
• Subtask 2: 45.9375 / 70