Submission #887108

#	Time	Username	Problem	Language	Result	Execution time	Memory
887108		Macker	Flood (IOI07_flood)	C++17	100 / 100	244 ms	25232 KiB

flood

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
#define all(v) v.begin(), v.end()

vector<array<int, 4>> adj;
vector<array<int, 4>> adji;
vector<int> res;
vector<int> vis;
int strt = -1;

bool dfs(int a, int dir, int r){
    for (int i = -1; i < 3; i++) {
        int j = (i + dir + 4) % 4;
        int b = adj[a][j];
        if(b == strt){
            if(vis[adji[a][j]] == r) res.push_back(adji[a][j]);
            adj[a][j] = -1;
            adj[b][(j + 2) % 4] = -1;
            return 1;
        } 
        if(b != -1){
            if(vis[adji[a][j]] == r){
                res.push_back(adji[a][j]);
                adj[a][j] = -1;
                adj[b][(j + 2) % 4] = -1;
            }
            vis[adji[a][j]] = r;
            vis[adji[b][(j + 2) % 4]] = r;
            if(dfs(b, j, r)){
                adj[a][j] = -1;
                adj[b][(j + 2) % 4] = -1;
                return 1;
            }
        }
    }
    return 0;
}

int main()
{
    int n; cin >> n;
    vector<array<int, 3>> pos(n);
    vector<int> pord(n);
    adj.resize(n, {-1, -1, -1, -1}); //up, left, down, right
    adji.resize(n, {-1, -1, -1, -1}); //up, left, down, right
    for (int i = 0; i < n; i++){
        cin >> pos[i][0] >> pos[i][1];
        pos[i][2] = i;
    }
    int w; cin >> w;
    vis.resize(w + 1, -1);
    for (int i = 1; i <= w; i++) {
        int a, b; cin >> a >> b; a--; b--;
        if(pos[a][1] == pos[b][1]){
            if(pos[a][0] > pos[b][0]){
                adj[a][0] = b;
                adj[b][2] = a;
                adji[a][0] = i;
                adji[b][2] = i;
            }
            else{
                adj[a][2] = b;
                adj[b][0] = a;
                adji[a][2] = i;
                adji[b][0] = i;
            }
        }
        else{
            if(pos[a][1] < pos[b][1]){
                adj[a][3] = b;
                adj[b][1] = a;
                adji[a][3] = i;
                adji[b][1] = i;
            }
            else{
                adj[a][1] = b;
                adj[b][3] = a;
                adji[a][1] = i;
                adji[b][3] = i;
            }
        }
    }
    sort(all(pos));

    for (auto p : pos) {
        if(adj[p[2]] == array<int, 4>({-1, -1, -1, -1})) continue;

        for (int i = 0; i < 4; i++) {
            if(adj[p[2]][i] != -1){
                strt = p[2];
                dfs(p[2], i, p[2]);
            }
        }
    }
    
    cout << res.size() << endl;
    for (auto &&i : res)
        cout << i << endl;
}

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