Submission #971312

#	Time	Username	Problem	Language	Result	Execution time	Memory
971312		Bodisha	Tracks in the Snow (BOI13_tracks)	C++17	67.19 / 100	1235 ms	1048576 KiB

tracks

#include <bits/stdc++.h>
#define MAX_D 4001
#define MAX_D 4001

using namespace std;

int h, w;
char meadow[MAX_D][MAX_D];
int component[MAX_D][MAX_D];
unordered_set<int> graph[MAX_D * MAX_D];

void floodfill(int x, int y, int cmp) {
    component[x][y] = cmp;
    if(x + 1 < h && meadow[x + 1][y] == meadow[x][y] && component[x + 1][y] == 0) {
        floodfill(x + 1, y, cmp);
    }
    if(x - 1 >= 0 && meadow[x - 1][y] == meadow[x][y] && component[x - 1][y] == 0) {
        floodfill(x - 1, y, cmp);
    }
    if(y + 1 < w && meadow[x][y + 1] == meadow[x][y] && component[x][y + 1] == 0) {
        floodfill(x, y + 1, cmp);
    }
    if(y - 1 >= 0 && meadow[x][y - 1] == meadow[x][y] && component[x][y - 1] == 0) {
        floodfill(x, y - 1, cmp);
    }
}

int main() {
    string tmps;
    cin >> h >> w;
    for(int i = 0; i < h; i++) {
        cin >> tmps;
        for(int j = 0; j < w; j++) {
            meadow[i][j] = tmps[j];
        }   
    }
    int cnt = 1;
    for(int i = 0; i < h; i++) {
        for(int j = 0; j < w; j++) {
            if(component[i][j] == 0 && meadow[i][j] != '.') {
                floodfill(i, j, cnt);
                cnt++;
            }
        }
    }
    for(int i = 0; i < h; i++) {
        for(int j = 0; j < w; j++) {
            if(meadow[i][j] == '.') {
                continue;
            }
            if(i + 1 < h && meadow[i + 1][j] != '.' && component[i + 1][j] != component[i][j] && graph[component[i + 1][j]].count(component[i][j]) == 0) {
                graph[component[i + 1][j]].insert(component[i][j]);
                graph[component[i][j]].insert(component[i + 1][j]);
            }
            if(i - 1 >= 0 && meadow[i - 1][j] != '.' && component[i - 1][j] != component[i][j] && graph[component[i - 1][j]].count(component[i][j]) == 0) {
                graph[component[i - 1][j]].insert(component[i][j]);
                graph[component[i][j]].insert(component[i - 1][j]);
            }  
            if(j + 1 < w && meadow[i][j + 1] != '.' && component[i][j + 1] != component[i][j] && graph[component[i][j + 1]].count(component[i][j]) == 0) {
                graph[component[i][j + 1]].insert(component[i][j]);
                graph[component[i][j]].insert(component[i][j + 1]);
            }  
            if(j - 1 >= 0 && meadow[i][j - 1] != '.' && component[i][j - 1] != component[i][j] && graph[component[i][j - 1]].count(component[i][j]) == 0) {
                graph[component[i][j - 1]].insert(component[i][j]);
                graph[component[i][j]].insert(component[i][j - 1]);
            }     
        }
    }
    int d[cnt];
    fill(d, d + cnt, -1);
    queue<pair<int, int>> q;
    d[component[0][0]] = 0;
    q.push({component[0][0], 0});
    while(!q.empty()) {
        pair<int, int> curr_node = q.front();
        q.pop();
        for(auto iter : graph[curr_node.first]) {
            if(d[iter] == -1) {
                d[iter] = curr_node.second + 1;
                q.push({iter, curr_node.second + 1});
            }
        }
    }
    int ans = 1;
    for(int i = 0; i < cnt; i++) {
        ans = max(ans, d[i] + 1);
    }
    cout << ans;
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 37.1875 / 70