Submission #897792

#	Time	Username	Problem	Language	Result	Execution time	Memory
897792		ivaziva	Mecho (IOI09_mecho)	C++17	84 / 100	125 ms	12124 KiB

mecho

#include <bits/stdc++.h>
 
using namespace std;
 
#define MAXN 810
 
long long n;
long long s;
char matrica[MAXN][MAXN];
long long dist1[MAXN][MAXN];///bee bfs
long long dist2[MAXN][MAXN];///mecho bfs
queue<pair<long long,long long>> bfsq1;
queue<pair<long long,long long>> bfsq2;
 
bool check(long long x,long long y)
{
    if (x>=1 and x<=n and y>=1 and y<=n and matrica[x][y]!='T') return true;
    else return false;
}
 
void bfs1()
{
    while (bfsq1.empty()==false)
    {
        long long x=bfsq1.front().first;
        long long y=bfsq1.front().second;
        bfsq1.pop();
        if (check(x+1,y) and dist1[x+1][y]==LLONG_MAX)
        {
            dist1[x+1][y]=dist1[x][y]+1;
            bfsq1.push({x+1,y});
        }
        if (check(x-1,y) and dist1[x-1][y]==LLONG_MAX)
        {
            dist1[x-1][y]=dist1[x][y]+1;
            bfsq1.push({x-1,y});
        }
        if (check(x,y+1) and dist1[x][y+1]==LLONG_MAX)
        {
            dist1[x][y+1]=dist1[x][y]+1;
            bfsq1.push({x,y+1});
        }
        if (check(x,y-1) and dist1[x][y-1]==LLONG_MAX)
        {
            dist1[x][y-1]=dist1[x][y]+1;
            bfsq1.push({x,y-1});
        }
    }
}
 
void bfs2(long long a,long long b,long long mid)
{
    for (long long i=1;i<=n;i++)
    {
        for (long long j=1;j<=n;j++) dist2[i][j]=LLONG_MAX;
    }
    dist2[a][b]=mid*s; bfsq2.push({a,b});
    while (bfsq2.empty()==false)
    {
        long long x=bfsq2.front().first;
        long long y=bfsq2.front().second;
        bfsq2.pop();
        if (check(x+1,y) and dist2[x+1][y]==LLONG_MAX)
        {
            long long d=dist2[x][y]+1;
            if (d<dist1[x+1][y]*s) dist2[x+1][y]=d;
            else dist2[x+1][y]=-1;
            if (dist2[x+1][y]!=-1) bfsq2.push({x+1,y});
        }
        if (check(x-1,y) and dist2[x-1][y]==LLONG_MAX)
        {
            long long d=dist2[x][y]+1;
            if (d<dist1[x-1][y]*s) dist2[x-1][y]=d;
            else dist2[x-1][y]=-1;
            if (dist2[x-1][y]!=-1) bfsq2.push({x-1,y});
        }
        if (check(x,y+1) and dist2[x][y+1]==LLONG_MAX)
        {
            long long d=dist2[x][y]+1;
            if (d<dist1[x][y+1]*s) dist2[x][y+1]=d;
            else dist2[x][y+1]=-1;
            if (dist2[x][y+1]!=-1) bfsq2.push({x,y+1});
        }
        if (check(x,y-1) and dist2[x][y-1]==LLONG_MAX)
        {
            long long d=dist2[x][y]+1;
            if (d<dist1[x][y-1]*s) dist2[x][y-1]=d;
            else dist2[x][y-1]=-1;
            if (dist2[x][y-1]!=-1) bfsq2.push({x,y-1});
        }
    }
}
 
int main()
{
    ios_base::sync_with_stdio(false);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>s;
    for (long long i=1;i<=n;i++)
    {
        for (long long j=1;j<=n;j++) dist1[i][j]=LLONG_MAX;
    }
    long long a,b;
    long long c,d;
    for (long long i=1;i<=n;i++)
    {
        for (long long j=1;j<=n;j++)
        {
            cin>>matrica[i][j];
            if (matrica[i][j]=='H')
            {
                dist1[i][j]=0;
                bfsq1.push({i,j});
            }
            if (matrica[i][j]=='M') {a=i;b=j;}
            if (matrica[i][j]=='D') {c=i;d=j;}
        }
    }
    bfs1();
    long long l=0;
    long long r=n*n;
    long long rez=-1;
    while (l<=r)
    {
        long long mid=(l+r)/2;
        bfs2(a,b,mid);
        if (dist2[c-1][d]!=LLONG_MAX and dist2[c-1][d]!=-1 and check(c-1,d)) {rez=mid;l=mid+1;}
        else if (dist2[c+1][d]!=LLONG_MAX and dist2[c+1][d]!=-1 and check(c+1,d)) {rez=mid;l=mid+1;}
        else if (dist2[c][d-1]!=LLONG_MAX and dist2[c][d-1]!=-1 and check(c,d-1)) {rez=mid;l=mid+1;}
        else if (dist2[c][d+1]!=LLONG_MAX and dist2[c][d+1]!=-1 and check(c,d+1)) {rez=mid;l=mid+1;}
        else r=mid-1;
    }
    cout<<rez<<endl;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:106:17: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
  106 |     long long c,d;
      |                 ^
mecho.cpp:106:15: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
  106 |     long long c,d;
      |               ^
mecho.cpp:128:13: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
  128 |         bfs2(a,b,mid);
      |         ~~~~^~~~~~~~~
mecho.cpp:128:13: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]

• Subtask 1: 84 / 100