Submission #1032175

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032175		GrindMachine	Flood (IOI07_flood)	C++17	43 / 100	198 ms	65536 KiB

flood

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*

refs:
some hidden tcs (to identify the bug)
read the edi a long time ago, remember some key ideas from there

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<int> dx = {-1,1,0,0};
vector<int> dy = {0,0,-1,1};

void solve(int test_case)
{
    ll n; cin >> n;
    vector<pll> a(n+5);
    rep1(i,n) cin >> a[i].ff >> a[i].ss;
    rep1(i,n) a[i].ff += 3, a[i].ss += 3;
    ll m; cin >> m;
    vector<pll> b(m+5);
    rep1(i,m) cin >> b[i].ff >> b[i].ss;
    set<array<ll,4>> st;

    rep1(i,m){
        auto [x1,y1] = a[b[i].ff];
        auto [x2,y2] = a[b[i].ss];

        // same col
        if(x1 == x2){
            if(y1 > y2) swap(y1,y2);
            for(int y = y1; y < y2; ++y){
                st.insert({x1-1,y,x1,y});
                st.insert({x1,y,x1-1,y});
            }
        }
        // same row
        else if(y1 == y2){
            if(x1 > x2) swap(x1,x2);
            for(int x = x1; x < x2; ++x){
                st.insert({x,y1-1,x,y1});
                st.insert({x,y1,x,y1-1});
            }
        }
        else{
            assert(0);
        }
    }

    ll siz = 0;
    rep1(i,n) amax(siz,a[i].ff), amax(siz,a[i].ss);

    ll dis[siz+5][siz+5];
    bool vis[siz+5][siz+5];
    memset(dis,0x3f,sizeof dis);
    memset(vis,0,sizeof vis);

    deque<pii> dq;
    dq.pb({0,0});
    dis[0][0] = 0;

    while(!dq.empty()){
        auto [i,j] = dq.front();
        dq.pop_front();

        if(vis[i][j]) conts;
        vis[i][j] = 1;

        rep(d,4){
            int i2 = i+dx[d], j2 = j+dy[d];
            if(i2 < 0 or i2 >= siz+5 or j2 < 0 or j2 >= siz+5) conts;
            if(st.count({i,j,i2,j2})){
                if(dis[i][j]+1 < dis[i2][j2]){
                    dq.pb({i2,j2});
                    dis[i2][j2] = dis[i][j]+1;
                }
            }
            else{
                if(dis[i][j] < dis[i2][j2]){
                    dq.push_front({i2,j2});
                    dis[i2][j2] = dis[i][j];
                }
            }
        }
    }

    vector<ll> ans;

    rep1(i,m){
        auto [x1,y1] = a[b[i].ff];
        auto [x2,y2] = a[b[i].ss];

        // same col
        if(x1 == x2){
            if(y1 > y2) swap(y1,y2);
            bool ok = true;
            for(int y = y1; y < y2; ++y){
                if(dis[x1-1][y] != dis[x1][y]){
                    ok = false;
                }
            }
            if(ok){
                ans.pb(i);
            }

            for(int y = y1; y < y2; ++y){
                assert(dis[x1-1][y] == dis[x1-1][y1]);
            }
        }
        // same row
        else if(y1 == y2){
            if(x1 > x2) swap(x1,x2);
            bool ok = true;
            for(int x = x1; x < x2; ++x){
                if(dis[x][y1-1] != dis[x][y1]){
                    ok = false;
                }
            }
            if(ok){
                ans.pb(i);
            }

            for(int x = x1; x < x2; ++x){
                assert(dis[x][y1-1] == dis[x1][y1-1]);
            }
        }
        else{
            assert(0);
        }
    }

    cout << sz(ans) << endl;
    trav(x,ans) cout << x << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 3 / 3
• Subtask 5: 10 / 10
• Subtask 6: 0 / 3
• Subtask 7: 0 / 3
• Subtask 8: 0 / 3
• Subtask 9: 0 / 3
• Subtask 10: 0 / 9
• Subtask 11: 0 / 9
• Subtask 12: 0 / 9
• Subtask 13: 0 / 9
• Subtask 14: 0 / 9