Submission #1235862

#	Time	Username	Problem	Language	Result	Execution time	Memory
1235862		vk3601h	Tropical Garden (IOI11_garden)	C++20	100 / 100	1308 ms	23952 KiB

garden

#include "garden.h"
#include "gardenlib.h"
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;

void count_routes(int N, int M, int P, int R[][2], int Q, int G[]) {
    vector<int> adj0(N, -1);
    vector<int> adj1(N, -1);
    
    for (int i = 0; i < M; i++) {
        int u = R[i][0];
        int v = R[i][1];
        if (adj0[u] == -1) adj0[u] = v;
        else if (adj1[u] == -1) adj1[u] = v;
        if (adj0[v] == -1) adj0[v] = u;
        else if (adj1[v] == -1) adj1[v] = u;
    }
    
    for (int i = 0; i < N; i++) {
        if (adj1[i] == -1) adj1[i] = adj0[i];
    }
    
    auto next_state = [&](int state) -> int {
        int u = state / 2;
        int s = state % 2;
        int w = (s == 0) ? adj0[u] : adj1[u];
        if (adj0[w] == u) return 2 * w + 1;
        else return 2 * w;
    };
    
    int total_states = 2 * N;
    vector<int> cycle_size(total_states, 0);
    vector<int> first_visit(total_states, -1);
    vector<bool> in_cycle(total_states, false);
    int time_stamp = 0;
    
    for (int start = 0; start < total_states; start++) {
        if (first_visit[start] != -1) continue;
        
        int slow = start, fast = start;
        do {
            slow = next_state(slow);
            fast = next_state(next_state(fast));
        } while (first_visit[slow] == -1 && first_visit[fast] == -1 && slow != fast);
        
        if (first_visit[slow] != -1) continue;
        
        if (slow == fast) {
            int cycle_start = slow;
            vector<int> cycle_nodes;
            int cur = cycle_start;
            do {
                cycle_nodes.push_back(cur);
                cur = next_state(cur);
            } while (cur != cycle_start);
            
            int len = cycle_nodes.size();
            for (int node : cycle_nodes) {
                cycle_size[node] = len;
                in_cycle[node] = true;
            }
        }
        
        int cur = start;
        int cnt = 0;
        while (first_visit[cur] == -1) {
            first_visit[cur] = time_stamp++;
            cur = next_state(cur);
            cnt++;
        }
    }
    
    int t0 = 2 * P;
    int t1 = 2 * P + 1;
    vector<int> dist0(total_states, -1);
    vector<int> dist1(total_states, -1);
    vector<vector<int>> rev_adj(total_states);
    
    for (int i = 0; i < total_states; i++) {
        int j = next_state(i);
        rev_adj[j].push_back(i);
    }
    
    queue<int> q0;
    dist0[t0] = 0;
    q0.push(t0);
    while (!q0.empty()) {
        int u = q0.front(); q0.pop();
        for (int v : rev_adj[u]) {
            if (dist0[v] == -1) {
                dist0[v] = dist0[u] + 1;
                q0.push(v);
            }
        }
    }
    
    queue<int> q1;
    dist1[t1] = 0;
    q1.push(t1);
    while (!q1.empty()) {
        int u = q1.front(); q1.pop();
        for (int v : rev_adj[u]) {
            if (dist1[v] == -1) {
                dist1[v] = dist1[u] + 1;
                q1.push(v);
            }
        }
    }
    
    int C0 = cycle_size[t0];
    int C1 = cycle_size[t1];
    
    for (int idx = 0; idx < Q; idx++) {
        long long K = G[idx];
        int ans = 0;
        
        for (int u = 0; u < N; u++) {
            int s0 = 2 * u;
            if (dist0[s0] != -1) {
                if (C0 == 0) {
                    if (dist0[s0] == K) ans++;
                } else {
                    if (K >= dist0[s0] && (K - dist0[s0]) % C0 == 0) 
                        ans++;
                }
            }
            if (dist1[s0] != -1) {
                if (C1 == 0) {
                    if (dist1[s0] == K) ans++;
                } else {
                    if (K >= dist1[s0] && (K - dist1[s0]) % C1 == 0) 
                        ans++;
                }
            }
        }
        answer(ans);
    }
}

• Subtask 1: 49 / 49
• Subtask 2: 20 / 20
• Subtask 3: 31 / 31