Submission #659073

#	Time	Username	Problem	Language	Result	Execution time	Memory
659073		ansgar	Mecho (IOI09_mecho)	C++17	73 / 100	216 ms	16616 KiB

mecho

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

#define int long long
#define vi vector<int>
#define vvi vector<vi>
#define pii pair<int,int>
#define vpii vector<pii>
#define vvpii vector<vpii>
#define vb vector<bool>
#define vc vector<char>
#define vvc vector<vc>
#define vvb vector<vb>
#define si set<int>
#define mii map<int,int>

const int mod=1e9+7;
const int N=2e5+1;
const int LN=LLONG_MAX/10;
vvc L;
int n,k;
vvi Bees;
vvi Bear;
vpii BeesLoc;
bool inside(int y,int x){
    return (y>=0 and y<n and x>=0 and x<n and L[y][x]!='T');
}
void bfsBees(){
    queue<pii> Q;
    for(auto B : BeesLoc){
        Q.push(B);
        Bees[B.first][B.second]=-1;
    }
    while(Q.size()){
        auto B=Q.front();
        int x=B.second;
        int y=B.first;
        Q.pop();
        if(inside(y-1,x) and Bees[y-1][x]>Bees[y][x]+1){
            Bees[y-1][x]=Bees[y][x]+1;
            Q.push({y-1,x});
        }
        if(inside(y+1,x) and Bees[y+1][x]>Bees[y][x]+1){
            Bees[y+1][x]=Bees[y][x]+1;
            Q.push({y+1,x});
        }
        if(inside(y,x-1) and Bees[y][x-1]>Bees[y][x]+1){
            Bees[y][x-1]=Bees[y][x]+1;
            Q.push({y,x-1});
        }
        if(inside(y,x+1) and Bees[y][x+1]>Bees[y][x]+1){
            Bees[y][x+1]=Bees[y][x]+1;
            Q.push({y,x+1});
        }
    }
}
void bfsBear(int sy,int sx,int w){
    queue<pii> Q;
    Q.push({sy,sx});
    Bear[sy][sx]=0;
    while(Q.size()){
        auto B=Q.front();
        int x=B.second;
        int y=B.first;
        Q.pop();
        if(inside(y-1,x) and Bear[y-1][x]>Bear[y][x]+1 and Bees[y-1][x]-((Bear[y][x]+1)/k)>=w){
            Bear[y-1][x]=Bear[y][x]+1;
            Q.push({y-1,x});
        }
        if(inside(y+1,x) and Bear[y+1][x]>Bear[y][x]+1 and Bees[y+1][x]-((Bear[y][x]+1)/k)>=w){
            Bear[y+1][x]=Bear[y][x]+1;
            Q.push({y+1,x});
        }
        if(inside(y,x-1) and Bear[y][x-1]>Bear[y][x]+1 and Bees[y][x-1]-((Bear[y][x]+1)/k)>=w){
            Bear[y][x-1]=Bear[y][x]+1;
            Q.push({y,x-1});
        }
        if(inside(y,x+1) and Bear[y][x+1]>Bear[y][x]+1 and Bees[y][x+1]-((Bear[y][x]+1)/k)>=w){
            Bear[y][x+1]=Bear[y][x]+1;
            Q.push({y,x+1});
        }
    }
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>k;
    L=vvc(n,vc(n));
    Bear=vvi(n,vi(n,LN));
    Bees=vvi(n,vi(n,LN));
    int sx,sy,ex,ey;
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            cin>>L[i][j];
            if(L[i][j]=='M')sy=i,sx=j;
            if(L[i][j]=='D')ey=i,ex=j;
            if(L[i][j]=='H')BeesLoc.emplace_back(i,j);
        }
    }
    bfsBees();
    int high=LN;
    int low=0;
    int res=-1;
    while(high>=low){
        int mid=(high+low)/2;
        Bear=vvi(n,vi(n,LN));
        bfsBear(sy,sx,mid);
        if(Bear[ey][ex]==LN)high=mid-1;
        else{
            res=mid;
            low=mid+1;
        }
    }
    cout<<res;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:108:19: warning: 'ey' may be used uninitialized in this function [-Wmaybe-uninitialized]
  108 |         if(Bear[ey][ex]==LN)high=mid-1;
      |                   ^
mecho.cpp:108:23: warning: 'ex' may be used uninitialized in this function [-Wmaybe-uninitialized]
  108 |         if(Bear[ey][ex]==LN)high=mid-1;
      |                       ^
mecho.cpp:107:16: warning: 'sy' may be used uninitialized in this function [-Wmaybe-uninitialized]
  107 |         bfsBear(sy,sx,mid);
      |         ~~~~~~~^~~~~~~~~~~
mecho.cpp:107:16: warning: 'sx' may be used uninitialized in this function [-Wmaybe-uninitialized]

• Subtask 1: 73 / 100