Submission #636872

#	Time	Username	Problem	Language	Result	Execution time	Memory
636872		Cross_Ratio	Synchronization (JOI13_synchronization)	C++14	100 / 100	1215 ms	25792 KiB

synchronization

#include <bits/stdc++.h>
using namespace std;
int DP1[200005];
int DP2[200005];
int par[200005][22];
int in[200005];
int out[200005];
int global_ETT = 0;
vector<vector<int>> adj;
void dfs(int c, int p) {
    in[c] = global_ETT;
    global_ETT++;
    par[c][0] = p;
    for(int n : adj[c]) {
        if(n==p) continue;
        dfs(n, c);
    }
    out[c] = global_ETT;
}
struct SegTree {
    vector<int> seg;
    int MAX;
    void init(int N) {
        int i;
        for(i=1;i<2*N;i*=2) {}
        seg.resize(i);
        MAX = i;
    }
    void update(int n) {
        n += MAX/2;
        n /= 2;
        while(n) {
            seg[n] = seg[2*n] + seg[2*n+1];
            n /= 2;
        }
    }
    void Edit(int n, int a) {
        seg[n+MAX/2] += a;
        update(n);
    }
    int sum(int s, int e, int n, int ns, int ne) {
        if(e<=ns||ne<=s) return 0;
        if(s<=ns&&ne<=e) return seg[n];
        int mid = ns + ne >> 1;
        return sum(s, e, 2*n, ns, mid) + sum(s, e, 2*n+1, mid, ne);
    }
};
array<int, 2> Edge[200005];
SegTree tree;
int Top(int n) {
    for(int i = 19; i >= 0; i--) {
        int n2 = par[n][i];
        if(n2 != -1 && tree.sum(0, in[n]+1, 1, 0, tree.MAX/2) == tree.sum(0, in[n2]+1, 1, 0, tree.MAX/2)) {
            n = n2;
        }
    }
    return n;
}
bool type[200005];
signed main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int N, M, Q;
    cin >> N >> M >> Q;
    adj.resize(N);
    int i, j;
    tree.init(N+5);
    for(i=0;i<N-1;i++) {
        cin >> Edge[i][0] >> Edge[i][1];
        Edge[i][0]--;
        Edge[i][1]--;
        adj[Edge[i][0]].push_back(Edge[i][1]);
        adj[Edge[i][1]].push_back(Edge[i][0]);
    }
    for(i=0;i<N;i++) DP1[i] = 1;
    dfs(0, -1);
    for(i=1;i<20;i++) {
        for(j=0;j<N;j++) {
            if(par[j][i-1]!=-1) {
                par[j][i] = par[par[j][i-1]][i-1];
            }
        }
    }
    for(i=0;i<N;i++) {
        tree.Edit(in[i], 1);
        tree.Edit(out[i], -1);
    }
    while(M--) {
        int x;
        cin >> x;
        x--;
        int u = Edge[x][0], v = Edge[x][1];
        if(par[u][0]==v) swap(u, v);
        int c = Top(u);
        if(type[x]) {
            DP1[v] = DP1[c];
            DP2[v] = DP1[c];
            tree.Edit(in[v], 1);
            tree.Edit(out[v], -1);
            type[x] = false;
        }
        else {
            DP1[c] += DP1[v] - DP2[v];
            tree.Edit(in[v], -1);
            tree.Edit(out[v], 1);
            type[x] = true;
        }
    }
    while(Q--) {
        int x;
        cin >> x;
        x--;
        cout << DP1[Top(x)] << '\n';
    }
}

Compilation message (stderr)

synchronization.cpp: In member function 'int SegTree::sum(int, int, int, int, int)':
synchronization.cpp:44:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   44 |         int mid = ns + ne >> 1;
      |                   ~~~^~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 10 / 10
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40