Submission #748150

#	Time	Username	Problem	Language	Result	Execution time	Memory
748150		onebit1024	Portals (BOI14_portals)	C++17	100 / 100	690 ms	43932 KiB

portals

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

#define pb push_back
#define all(c) c.begin(), c.end()
#define endl "\n"

const double PI=3.141592653589;


void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define dbg(x...) cerr << "LINE(" << __LINE__ << ") -> " <<"[" << #x << "] = ["; _print(x)
#else
#define dbg(x...)
#endif

int n,m;
const int N = 1005;
int a[N][N],dist[N][N],wall[N][N],dp[N][N][4];
vector<pair<int,int>>neigh(int i, int j){
    vector<pair<int,int>>res;
    if(i < n)res.pb({i+1,j});
    if(i > 1)res.pb({i-1,j});
    if(j < m)res.pb({i,j+1});
    if(j > 1)res.pb({i,j-1});
    return res;
}

void solve()
{
    cin >> n >> m;

    priority_queue<vector<int>,vector<vector<int>>,greater<vector<int>>>pq;
    int ex = 0, ey = 0;
    
    for(int i = 0;i<=n+1;++i){
        for(int j = 0;j<=m+1;++j){
            wall[i][j] = dist[i][j] = 1e9;
            a[i][j] = 1;
        }
    }
    for(int i = 1;i<=n;++i){
        for(int j = 1;j<=m;++j){
            char x;
            cin >> x;
            if(x=='.')a[i][j] = 0;
            else if(x=='C')ex = i,ey = j,a[i][j]=0;
            else if(x=='S')pq.push({0,i,j}),dist[i][j] = 0,a[i][j]=0;
        }
    }
    /*
    dp[i][j][0] -> right
    1 -> left
    2 -> up
    3 -> down
    */
    for(int i = 1;i<=n;++i){
        int prev = m+1;
        for(int j = m;j>=1;--j){
            if(a[i][j])prev = j;
            dp[i][j][0] = prev;
        }
        prev = 0;
        for(int j = 1;j<=m;++j){
            if(a[i][j])prev = j;
            dp[i][j][1] = prev;
        }
    }
    for(int j = 1;j<=m;++j){
        int prev = 0;
        for(int i = 1;i<=n;++i){
            if(a[i][j])prev = i;
            dp[i][j][2] = prev;
        }
        prev = n+1;
        for(int i = n;i>=1;--i){
            if(a[i][j])prev = i;
            dp[i][j][3] = prev;
        }
    }
    vector<vector<int>>vis(n+2, vector<int>(m+2)); // closest wall cell
    queue<pair<int,int>>q;
    for(int i = 0;i<=n+1;++i){
        for(int j = 0;j<=m+1;++j){
            if(a[i][j]){
                wall[i][j] = 0;
                q.push({i,j});
            }
        }
    }
    while(!q.empty()){
        int i = q.front().first, j = q.front().second;
        q.pop();
        if(vis[i][j])continue;
        vis[i][j] = 1;
        for(auto &[x,y] : neigh(i,j)){
            if(a[x][y])continue;
            wall[x][y] = min(wall[x][y],wall[i][j]+1);
            q.push({x,y});
        }
    }
    while(!pq.empty()){
        int d = pq.top()[0], i = pq.top()[1], j = pq.top()[2];
        pq.pop();

        if(dist[i][j]!=d)continue;
        for(auto &[x,y] : neigh(i,j)){
            if(a[x][y])continue;
            int curr_dist = dist[x][y], new_dist = dist[i][j]+1;
            if(new_dist < curr_dist){
                dist[x][y] = new_dist;
                pq.push({new_dist, x, y});
            }
        }
        int val = wall[i][j];
        for(auto w : {dp[i][j][0], dp[i][j][1]}){
            int y = w+1;
            if(w > j)y = w-1;
            int x = i;
            int curr_dist = dist[x][y], new_dist = dist[i][j]+val;
            if(new_dist < curr_dist){
                dist[x][y] = new_dist;
                pq.push({new_dist, x, y});
            }
        }
        for(auto w : {dp[i][j][2], dp[i][j][3]}){
            int x = w+1;
            if(w > i)x = w-1;

            int y = j;
            int curr_dist = dist[x][y], new_dist = dist[i][j]+val;
            if(new_dist < curr_dist){
                dist[x][y] = new_dist;
                pq.push({new_dist, x, y});
            }
        }
    }
    cout << dist[ex][ey];
}   

int32_t main()
{

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);


    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    

    int T=1;
    for(int i = 1;i<=T;++i)
    {
        // cout << "Case #" << i << ": ";
        solve();
    }
}

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