Submission #696413

#	Time	Username	Problem	Language	Result	Execution time	Memory
696413		Cross_Ratio	Through Another Maze Darkly (CCO21_day1problem3)	C++14	4 / 25	9073 ms	41140 KiB

Main

#include <bits/stdc++.h>
#define int long long
using namespace std;
vector<int> adj[800005];
int num[800005];
void dfs(int c, int p) {
    int i, j;
    if(p == -1) {
        int n = num[c];
        vector<int> V(adj[c].size());
        int sz = adj[c].size();
        for(i=0;i<sz;i++) {
            V[i] = adj[c][(i+n)%sz];
        }
        adj[c] = V;
        num[c] = (num[c] + sz - n) % sz;
    }
    else {
        int n = -1;
        int sz = adj[c].size();
        for(i=0;i<sz;i++) {
            if(adj[c][i]==p) n = i;
        }
        vector<int> V(sz);
        for(i=0;i<sz;i++) {
            V[i] = adj[c][(i+n)%sz];
        }
        adj[c] = V;
        num[c] = (num[c] + sz - n) % sz;
    }
    for(int n : adj[c]) {
        if(n ==p) continue;
        dfs(n, c);
    }
}
int sz[800005];
bool B[800005];
int dfs_cnt = 0;
int A[1600005];
int C[800005];
int par[800005];
int ord[800005];
void dfs2(int c, int p) {
    sz[c] = 1;
    par[c] = p;
    C[c] = dfs_cnt;
    for(int n : adj[c]) {
        if(n==p) continue;
        A[dfs_cnt++] = c;
        dfs2(n, c);
        ord[c]++;
        sz[c] += sz[n];
    }
    if(sz[c] == 1) B[c] = true;
    A[dfs_cnt++] = c;
}
vector<array<int, 2>> Query;
int ans[800005];
signed main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int N, Q;
    cin >> N >> Q;
    int i, j;
    for(i=0;i<N;i++) {
        int k;
        cin >> k;
        for(j=0;j<k;j++) {
            int c;
            cin >> c;
            adj[i].push_back(c-1);
        }
        num[i] = 1 % k;
    }
    dfs(0, -1);
    dfs2(0, -1);
    //cout << "dfs done\n";
    int ma = 0;
    for(i=0;i<Q;i++) {
        int a;
        cin >> a;
        //a = i+1;
        if(a >= N*N) {
            a = (a - N*N) % (2*(N-1)) + N*N;
        }
        ma = max(ma, a);
        Query.push_back({a, i});
    }
    sort(Query.begin(),Query.end());
    int pt = 0, cnt = 0;
    int qt = 0;
    for(i=0;i<N;i++) {
        if(B[i] && par[i] != -1) ord[par[i]]--;
    }
    //cout << "Finding Graph\n";
    while(qt < Query.size() && !B[0]) {
        //cout << pt << ' ' << cnt << '\n';
        //for(i=0;i<N;i++) cout << B[i] << ' ';
        //cout << '\n';
        if(B[pt]) {
            //cout << pt << " is ON\n";
            //cout << qt << ' ' << Query[qt][0] << '\n';
            while(qt < Query.size() && Query[qt][0] <= cnt + 2 * (sz[pt]-1)+1) {
                //cout << "qt is " << qt << '\n';
                int v = Query[qt][0] - cnt;
                ans[Query[qt][1]] = A[C[pt]+v];
                //cout << C[pt] + v << " :: " << Query[qt][1] << ' ' << A[C[pt]+v] << '\n';
                qt++;
            }
            cnt += 2*(sz[pt] - 1)+1;
            pt = par[pt];
        }
        else {
            cnt++;
            int p2 = adj[pt][num[pt]];
            num[pt] = (num[pt] + 1) % adj[pt].size();
            if(p2 == par[pt] && ord[pt]==0) {
                B[pt] = true;
                if(par[pt] != -1) ord[par[pt]]--;
            }
            if(p2 == par[pt] && p2 == 0 && ord[0] == 0 && num[0] == 0) {
                B[0] = true;
            }
            pt = p2;
            while(qt < Query.size() && Query[qt][0]==cnt) {
                //cout << "qts is " << qt << '\n';
                ans[Query[qt][1]] = pt;
                qt++;
            }
        }
    }
    while(qt < Query.size()) {
        int v = (Query[qt][0] - cnt) % (2*(N-1));
        ans[Query[qt][1]] = A[v];
        qt++;
    }
    for(i=0;i<Q;i++) cout <<ans[i]+1 << '\n';
}

Compilation message (stderr)

Main.cpp: In function 'void dfs(long long int, long long int)':
Main.cpp:7:12: warning: unused variable 'j' [-Wunused-variable]
    7 |     int i, j;
      |            ^
Main.cpp: In function 'int main()':
Main.cpp:97:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |     while(qt < Query.size() && !B[0]) {
      |           ~~~^~~~~~~~~~~~~~
Main.cpp:104:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  104 |             while(qt < Query.size() && Query[qt][0] <= cnt + 2 * (sz[pt]-1)+1) {
      |                   ~~~^~~~~~~~~~~~~~
Main.cpp:126:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  126 |             while(qt < Query.size() && Query[qt][0]==cnt) {
      |                   ~~~^~~~~~~~~~~~~~
Main.cpp:133:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::array<long long int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  133 |     while(qt < Query.size()) {
      |           ~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 4 / 4
• Subtask 3: 0 / 12
• Subtask 4: 0 / 5