Submission #990091

#	Time	Username	Problem	Language	Result	Execution time	Memory
990091		bachhoangxuan	Mecho (IOI09_mecho)	C++17	95 / 100	131 ms	12132 KiB

mecho

// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
- insert(x),erase(x)
- find_by_order(k): return iterator to the k-th smallest element
- order_of_key(x): the number of elements that are strictly smaller
*/
#include<bits/stdc++.h>
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
uniform_real_distribution<> pp(0.0,1.0);
#define int long long
#define ld long double
#define pii pair<int,int>
#define piii pair<int,pii>
#define mpp make_pair
#define fi first
#define se second
const long long inf=1e18;
const int mod=998244353;
const int maxn=805;
const int B=650;
const int maxs=655;
const int maxm=200005;
const int maxq=1000005;
const int maxl=25;
const int maxa=1000000;
const int root=3;
int power(int a,int n){
    int res=1;
    while(n){
        if(n&1) res=res*a%mod;
        a=a*a%mod;n>>=1;
    }
    return res;
}
const int iroot=power(3,mod-2);
const int base=101;

int sx,sy,tx,ty;
int n,S,d[maxn][maxn],dd[maxn][maxn];
char c[maxn][maxn];
int dx[]={0,0,1,-1},
    dy[]={1,-1,0,0};

bool check(int k){
    memset(dd,-1,sizeof(dd));
    dd[sx][sy]=k*S;
    queue<pii> q;
    q.push({sx,sy});
    //cout << "check " << k << '\n';
    while(!q.empty()){
        auto [x,y]=q.front();q.pop();
        //cout << x << ' ' << y << ' ' << dd[x][y] << '\n';
        if(x==tx && y==ty) return true;
        if(dd[x][y]/S>=d[x][y]) continue;
        for(int t=0;t<4;t++){
            int xt=x+dx[t],yt=y+dy[t];
            if(xt<=0 || yt<=0 || xt>n || yt>n || c[xt][yt]=='T' || dd[xt][yt]!=-1) continue;
            dd[xt][yt]=dd[x][y]+1;
            q.push({xt,yt});
        }
    }
    return false;
}

void solve(){
    cin >> n >> S;
    memset(d,-1,sizeof(d));
    queue<pii> q;
    for(int i=1;i<=n;i++) for(int j=1;j<=n;j++){
        cin >> c[i][j];
        if(c[i][j]=='H'){
            d[i][j]=0;
            q.push({i,j});
        }
        else if(c[i][j]=='M') sx=i,sy=j;
        else if(c[i][j]=='D') tx=i,ty=j;
    }
    while(!q.empty()){
        auto [x,y]=q.front();q.pop();
        //cout << x << ' ' << y << ' ' << d[x][y] << '\n';
        for(int t=0;t<4;t++){
            int xt=x+dx[t],yt=y+dy[t];
            if(xt<=0 || yt<=0 || xt>n || yt>n || c[xt][yt]=='T' || d[xt][yt]!=-1) continue;
            d[xt][yt]=d[x][y]+1;
            q.push({xt,yt});
        }
    }
    int l=0,r=n*n,res=-1;
    while(l<=r){
        int mid=(l+r)>>1;
        if(check(mid)) res=mid,l=mid+1;
        else r=mid-1;
    }
    cout << res << '\n';
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    int test=1;//cin >> test;
    while(test--) solve();
}

• Subtask 1: 95 / 100