Submission #557309

#	Time	Username	Problem	Language	Result	Execution time	Memory
557309		krit3379	Mecho (IOI09_mecho)	C++17	54 / 100	219 ms	9152 KiB

mecho

#include<bits/stdc++.h>
using namespace std;
#define N 805
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

struct A{
    int x,y,w,cnt;
};

int dis[N][N],di[4]={1,-1,0,0},dj[4]={0,0,1,-1},ans=-1;
int n,step,sx,sy,ex,ey;
char s[N];
pair<int,int> dp[N][N];
vector<pair<int,int>> hive;
bitset<N> tree[N],vis[N];
queue<A> q;

bool sol(int mid){
    if(mid>=dis[sx][sy])return false;
    int i,j,k;
    for(i=1;i<=n;i++){
        vis[i]=0;
        for(j=1;j<=n;j++)dp[i][j]={1e9,1e9};
    }
    q.push({sx,sy,step,mid});
    while(!q.empty()){
        auto [x,y,w,cnt]=q.front();
        q.pop();
        if(vis[x][y])continue;
        vis[x][y]=true;
        for(k=0;k<4;k++){
            int xx=x+di[k],yy=y+dj[k];
            if(xx>0&&xx<=n&&yy>0&&yy<=n&&!vis[xx][yy]&&!tree[xx][yy]){
                if(w==step&&dis[xx][yy]>=cnt+1&&make_pair(cnt+1,1)<dp[xx][yy])q.push({xx,yy,1,cnt+1}),dp[xx][yy]=make_pair(cnt+1,1);
                if(w<step&&dis[xx][yy]>=cnt&&make_pair(cnt,1)<dp[xx][yy])q.push({xx,yy,w+1,cnt}),dp[xx][yy]=make_pair(cnt,w+1);
            }
        }
    }
    return vis[ex][ey];
}

int main(){
    int i,j,k,l,r,mid;
    scanf("%d %d",&n,&step);
    for(i=1;i<=n;i++){
        scanf(" %s",s+1);
        for(j=1;j<=n;j++){
            if(s[j]=='T')tree[i][j]=true;
            else if(s[j]=='M')sx=i,sy=j;
            else if(s[j]=='D')ex=i,ey=j;
            else if(s[j]=='H')hive.push_back({i,j});
            dis[i][j]=1e9;
        }
    }
    for(auto [x,y]:hive)q.push({x,y,0});
    while(!q.empty()){
        auto [x,y,w,cnt]=q.front();
        q.pop();
        if(vis[x][y])continue;
        vis[x][y]=true;
        dis[x][y]=w;
        for(k=0;k<4;k++){
            int xx=x+di[k],yy=y+dj[k];
            if(xx>0&&xx<=n&&yy>0&&yy<=n&&!vis[xx][yy]&&!tree[xx][yy]&&(xx!=ex||yy!=ey))q.push({xx,yy,w+1});
        }
    }
    l=0,r=1e9;
    while(l<=r){
        mid=(l+r)/2;
        if(sol(mid))ans=mid,l=mid+1;
        else r=mid-1;
    }
    printf("%d",ans);
    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:45:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     scanf("%d %d",&n,&step);
      |     ~~~~~^~~~~~~~~~~~~~~~~~
mecho.cpp:47:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         scanf(" %s",s+1);
      |         ~~~~~^~~~~~~~~~~

• Subtask 1: 54 / 100