Submission #1260837

#	Time	Username	Problem	Language	Result	Execution time	Memory
1260837		_unknown_2010	Mecho (IOI09_mecho)	C++20	27 / 100	167 ms	6904 KiB

mecho

// #ifndef khos
// #pragma GCC optimize ("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #endif

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#ifdef khos
    #include "t_debug.cpp"
#else
    #define debug(...) 42
#endif
using namespace std;
using namespace __gnu_pbds;
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using indexed_multiset = tree<pair<int,int>, null_type, less<pair<int,int>>, rb_tree_tag, tree_order_statistics_node_update>;

// #define int int64_t
#define vi vector
#define ss second
#define ff first
#define TESTCASES
#define all(x) (x).begin(), (x).end()
const int mod = 1e9+7;
const int MAXN=4e6;
const int inf=1e9;
vi<int> dx={1, -1, 0, 0};
vi<int> dy={0, 0, 1, -1};
// ... (sarlavha va includes o'zi kabi)
void solution() {
    int n,s;
    cin >> n >> s;
    vi<string> a(n);
    const int INF = 1e9;
    vi<vi<int>> dist(n, vi<int> (n, INF));
    queue<pair<int,int>> q;
    int sx=-1, sy=-1, ex=-1, ey=-1;
    for(int i=0; i<n; i++){
        cin >> a[i];
        for(int j=0; j<n; j++){
            if(a[i][j]=='H'){
                dist[i][j]=0;
                q.push({i, j});
            }
            if(a[i][j]=='M'){
                sx=i; sy=j;
            }
            if(a[i][j]=='D'){
                ex=i; ey=j;
            }
        }
    }
    auto isvalid = [&](int nx, int ny) -> bool {
        if(nx<0 || ny<0) return false;
        if(nx>=n || ny>=n) return false;
        if(a[nx][ny]!='G' && a[nx][ny]!='M') return false;
        return true;
    };
    while(!q.empty()){
        auto [x,y]=q.front(); q.pop();
        for(int i=0;i<4;i++){
            int nx=x+dx[i], ny=y+dy[i];
            if(isvalid(nx, ny) && dist[nx][ny]==INF){
                dist[nx][ny]=dist[x][y]+1;
                q.push({nx, ny});
            }
        }
    }

    int l=-1, r=n*n;
    while(l<r){
        int mid=(l+r+1)/2;
        queue<pair<int,int>> qq;
        bool ok = false;
        // if bees already at start at or before mid -> impossible
        if (dist[sx][sy] <= mid) {
            ok = false;
        } else {
            qq.push({sx, sy});
            vi<vi<char>> vis(n, vi<char>(n,0));
            vi<vi<int>> mt(n, vi<int>(n,0));
            vis[sx][sy]=1; mt[sx][sy]=0;
            while(!qq.empty() && !ok){
                auto [x,y]=qq.front(); qq.pop();
                for(int i=0;i<4;i++){
                    int nx=x+dx[i], ny=y+dy[i];
                    // if stepping straight into home
                    if(nx==ex && ny==ey){
                        int needed = (mt[x][y] + 1 + s - 1) / s;
                        if (dist[ex][ey] > mid + needed) { ok = true; break; }
                        else continue;
                    }
                    if(!isvalid(nx, ny)) continue;
                    if(vis[nx][ny]) continue;
                    int needed = (mt[x][y] + 1 + s - 1) / s;
                    if(dist[nx][ny] > mid + needed){
                        vis[nx][ny]=1;
                        mt[nx][ny]=mt[x][y]+1;
                        qq.push({nx, ny});
                    }
                }
            }
        }
        if(ok) l = mid;
        else r = mid-1;
    }
    cout << l << '\n';
}

int32_t main(){
    clock_t tStart = clock();
    // freopen("atlarge.in", "r", stdin);
    // freopen("atlarge.out", "w", stdout);
    #ifdef khos
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    std::ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int q = 1;
    #ifdef TESTCASES
        // cin >> q;
    #endif
    while(q--) {
        solution();
        cout << '\n';
    }
    cerr<<fixed<<setprecision(3)<<"\nTime Taken: "<<(double)(clock()- tStart)/CLOCKS_PER_SEC<<endl;
}

• Subtask 1: 27 / 100