제출 #877716

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
877716		asli_bg	Tracks in the Snow (BOI13_tracks)	C++11	100 / 100	636 ms	174864 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef pair<int, int> pii;
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define MOD 1000000007
 
const int MAXN=4e3+1;
 
//bool vis[MAXN][MAXN];
 
int grid[MAXN][MAXN];
 
int h,w;
 
int xyon[4]={1,0,-1,0};
int yyon[4]={0,-1,0,1};
 

bool isvalid(int x,int y){
    if(x>=h or x<0 or y>=w or y<0) return false;
    if(grid[x][y]==-1) return false;
    return true;
}

int d[MAXN][MAXN];

int ans=1;
 
void bfs(int x,int y){
    deque<pii> q;
    q.push_back({x,y});
    //vis[x][y]=true;
    d[x][y]=1;
 
    while(q.size()){
        auto el=q.front();
        q.pop_front();

        ans=max(ans,d[el.fi][el.se]);
 
        for(int i=0;i<4;i++){
            int newx=el.fi+xyon[i];
            int newy=el.se+yyon[i];
 
            if(isvalid(newx,newy) and d[newx][newy]==0){
                //vis[newx][newy]=true;

                if(grid[newx][newy]==grid[el.fi][el.se]){
                    d[newx][newy]=d[el.fi][el.se];
                    q.push_front({newx,newy});
                }
                else{
                    d[newx][newy]=d[el.fi][el.se]+1;
                    q.push_back({newx,newy});
                }
                //cout<<"distance of "<<newx<<'-'<<newy<<" is: "<<d[newx][newy]<<endl;
            }
 
        }

        //grid[el.fi][el.se]=!grid[el.fi][el.se];
    }
}
 
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); 
 
    cin>>h>>w;
 
    map<char,int> anim;
    anim['F']=1;
    anim['R']=0;
    anim['.']=-1;

    //cout<<d[0][2]<<endl;
 
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            char c;
            cin>>c;
            grid[i][j]=anim[c];
        }
    }
 
    bfs(0,0);
    cout<<ans<<endl;
    //cout<<d[h][w]<<endl;
 
}

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