Submission #625895

#	Time	Username	Problem	Language	Result	Execution time	Memory
625895		goodluck2020	Portals (BOI14_portals)	C++14	100 / 100	352 ms	37692 KiB

portals

#include <bits/stdc++.h>
#define task "SNAKE"
 
using namespace std;
const int N = 1e3 + 5;
int n, m, A[N][N];
struct Data
{
    int x, y;
} S, C, D;
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
struct Data2
{
    int x, y, w;
} P;
struct cmp
{
    bool operator() (Data2 A, Data2 B)
    {
        return A.w > B.w;
    }
};
int Up[N][N], Down[N][N], Left[N][N], Right[N][N];
void init()
{
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++)
        {
            Left[i][j] = Left[i][j-1] + 1;
            if(A[i][j] == 0) Left[i][j] = 0;
        }
        for(int j = m; j >= 1; j--)
        {
            Right[i][j] = Right[i][j + 1] + 1;
            if(A[i][j] == 0) Right[i][j] = 0;
        }
    }
    for(int j = 1; j <= m; j++)
    {
        for(int i = 1; i <= n; i++)
        {
            Up[i][j] = Up[i-1][j] + 1;
            if(A[i][j] == 0) Up[i][j] = 0;
        }
        for(int i = n; i >= 1; i--)
        {
            Down[i][j] = Down[i + 1][j] + 1;
            if(A[i][j] == 0) Down[i][j] = 0;
        }
    }
}
priority_queue < Data2, vector < Data2 > , cmp > pq;
namespace sub5
{
    queue < Data > Q;
    int Visited[N][N], dist[N][N], wall[N][N];
    void Build()
    {
        for(int i = 0; i <= n + 1; i++)
            for(int j = 0; j <= m + 1; j++)
        if(A[i][j] == 0) Q.push({i, j}), Visited[i][j] = 1;
        while(!Q.empty())
        {
            Data D = Q.front(); Q.pop();
            for(int i = 0; i < 4; i++)
            {
                int x = D.x + dx[i];
                int y = D.y + dy[i];
                if(A[x][y] && !Visited[x][y])
                {
                    Q.push({x, y});
                    wall[x][y] = wall[D.x][D.y] + 1;
                    Visited[x][y] = 1;
                }
            }
        }
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= m; j++) Visited[i][j] = 0, dist[i][j] = 1e9;
 
    }
    void Go(int x, int y, int cost)
    {
        if(dist[x][y] <= dist[P.x][P.y] + cost) return;
        dist[x][y] = dist[P.x][P.y] + cost;
        pq.push({x, y, dist[x][y]});
    }
    void solve()
    {
        Build();
        pq.push({S.x, S.y, 0}); dist[S.x][S.y] = 0;
        while(!pq.empty())
        {
            P = pq.top(); pq.pop();
            for(int i = 0; i < 4; i++)
            {
                int x = P.x + dx[i];
                int y = P.y + dy[i];
                if(A[x][y]) Go(x, y, 1);
            }
                int x, y;
                x = P.x - (Up[P.x][P.y] - 1); y = P.y;
                Go(x, y, wall[P.x][P.y]);
                x = P.x + (Down[P.x][P.y] - 1); y = P.y;
                Go(x, y, wall[P.x][P.y]);
                x = P.x; y = P.y - (Left[P.x][P.y] - 1);
                Go(x, y, wall[P.x][P.y]);
                x = P.x; y = P.y + (Right[P.x][P.y] - 1);
                Go(x, y, wall[P.x][P.y]);
        }
        cout << dist[C.x][C.y];
    }
}
int main()
{
    if(fopen(task ".inp","r"))
    {
        freopen(task ".inp","r",stdin);
        freopen(task ".out","w",stdout);
    }
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n >> m;
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++)
        {
            char ch;
            cin >> ch;
            if(ch == 'S') S = {i, j};
            if(ch == 'C') C = {i, j};
            if(ch != '#') A[i][j] = 1;
        }
    init();
    sub5::solve();
}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:119:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  119 |         freopen(task ".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
portals.cpp:120:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  120 |         freopen(task ".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 30 / 30