Submission #499619

#	Time	Username	Problem	Language	Result	Execution time	Memory
499619		_AnKahng	Mecho (IOI09_mecho)	C++14	15 / 100	147 ms	4612 KiB

mecho

#include<bits/stdc++.h>
#define fi first
#define sc second
#define fr(i,a,b) for(int i=a;i<=b;i++)
#define fo(i,a,b) for(int i=a;i<=b;i++)
using namespace std;

const int H[] = {-1,-1,1,1};
const int M = 805;
int n,s,f[M][M];
bool cx[M][M];
pair<int,int> st,fn;
string a[M];
struct dota{
    int x,y,d;
};

void BFS_hive(){
    queue<dota> q;
    memset(cx,false,sizeof(cx));
    fo(i,1,n)
        fo(j,1,n) {
            if(a[i][j] != 'T') cx[i][j] = true;
            if(a[i][j] == 'H') q.push({i,j,0}), f[i][j] = 0, cx[i][j] = false;
        }
    while(!q.empty()){
        int x = q.front().x, y = q.front().y, d = q.front().d;
        q.pop();
        f[x][y] = d;
        int xi,yi;
        fo(k,0,3){
            if(k % 2) xi = x + H[k], yi = y;
            else xi = x, yi = y + H[k];
            if(cx[xi][yi]) q.push({xi,yi,d+1}), cx[xi][yi] = false;
        }
    }
}

bool check(int t){
    queue<dota> q;
    memset(cx,false,sizeof(cx));
    fo(i,1,n)
        fo(j,1,n) if(a[i][j] != 'T') cx[i][j] = true;
    q.push({st.fi,st.sc,0});
    cx[st.fi][st.sc] = false;
    while(!q.empty()){
        int x = q.front().x, y = q.front().y, d = q.front().d;
        q.pop();
        if(x == fn.fi && y == fn.sc) return true;
        int xi,yi;
        fo(k,0,3){
            if(k % 2) xi = x + H[k], yi = y;
            else xi = x, yi = y + H[k];
            if(cx[xi][yi] && (d + 1) / s < f[xi][yi] - t) q.push({xi,yi,d+1}), cx[xi][yi] = false;
        }
    }
    return false;
}

int main()
{
    ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin >> n >> s;
    fo(i,1,n) cin >> a[i], a[i] = "*" + a[i];
    fo(i,1,n)
        fo(j,1,n)
            if(a[i][j] == 'M') st = {i,j};
            else if(a[i][j] == 'D') fn = {i,j};
    BFS_hive();
    //fo(i,1,n) fo(j,1,n) cout << f[i][j]<<" \n"[j == n];
    int l = 0, r = n, mid,res;
    while(l <= r){
        mid = (l + r) / 2;
        if(check(mid)) l = mid+1, res = mid;
        else r = mid-1;
    }
    cout << res;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:77:13: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
   77 |     cout << res;
      |             ^~~

• Subtask 1: 15 / 100