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Submission #488688

# Submission time Handle Problem Language Result Execution time Memory
488688 2021-11-20T05:11:33 Z SirCovidThe19th Special graph (IZhO13_specialg) C++17
100 / 100
 244 ms 14588 KB 
#include <bits/stdc++.h>
using namespace std;

#define FOR(i, x, y) for (int i = x; i < y; i++)

const int mx = 1e5 + 5;

int n, q, to[mx], dep[mx], tin[mx], tout[mx], ti, cyc[mx]; bool vis[mx], active[mx];
vector<int> startDFS, adj[mx]; 

template<int sz> struct segTreeRP{
    int seg[sz * 2];

    int comb(int a, int b){
        return tin[a] > tin[b] ? a : b; //we want lower node so the one with greatest tin val
    }
    void upd(int l, int r, int v){
        for (l += sz, r += sz; l <= r; r /= 2, l /= 2){
            if (l % 2 == 1) seg[l] = comb(seg[l], v), l++; 
            if (r % 2 == 0) seg[r] = comb(seg[r], v), r--;
        }
    }
    int qry(int i){
        int ret = 0;
        for (i += sz; i; i /= 2) ret = comb(ret, seg[i]);
        return ret;
    }
};segTreeRP<mx> st;

void findStartPts(int cur){
    active[cur] = vis[cur] = 1; int nxt = to[cur]; 
    if (!nxt) startDFS.push_back(cur); //endpoint of chain
    else{
        if (!vis[nxt]) findStartPts(nxt);
        else if (active[nxt]) startDFS.push_back(cur); //part of cycle
    }
    active[cur] = 0;
}
bool isAnc(int A, int B){
    return tin[A] <= tin[B] and tout[A] >= tout[B];
}
void dfs(int cur){
    tin[cur] = ++ti; 
    for (int nxt : adj[cur]){
        if (!tin[nxt]) dep[nxt] = dep[cur] + 1, dfs(nxt);
        else cyc[nxt] = cur;
    }
    tout[cur] = ti;
}
void rem(int X){ //remove edge outgoing from X
    if (cyc[X]) cyc[X] = 0;
    else st.upd(tin[X], tout[X], X);
}
int solve(int A, int B){ //A goes to B
    int ret = 0, root = st.qry(tin[A]);
    
    if (!isAnc(B, A)){ //go to root and use cycle
        ret += dep[A] - dep[root] + 1;
        A = cyc[root]; root = st.qry(tin[A]); //we can be in a "new" tree so lets upd root
    }
    if (isAnc(B, A) and tin[B] >= tin[root]) ret += dep[A] - dep[B];
    else ret = -1;

    return ret;
}

int main(){
    cin >> n;
    FOR(i, 1, n + 1){
        cin >> to[i];
        if (to[i]) adj[to[i]].push_back(i); 
    }
    FOR(i, 1, n + 1) if (!vis[i]) findStartPts(i);
    for (int i : startDFS){
        dfs(i);
        st.upd(tin[i], tout[i], i);
    }
    cin >> q;
    while (q--){
        int tp, A, B; cin >> tp;
        if (tp == 1) cin >> A, rem(A);
        else cin >> A >> B, cout<<solve(A, B)<<"\n";
    }
}

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 2764 KB Output is correct
2 Correct 7 ms 2764 KB Output is correct
3 Correct 7 ms 2764 KB Output is correct
4 Correct 18 ms 2772 KB Output is correct
5 Correct 8 ms 2764 KB Output is correct
6 Correct 40 ms 2856 KB Output is correct
7 Correct 40 ms 2852 KB Output is correct
8 Correct 39 ms 2852 KB Output is correct
9 Correct 37 ms 2848 KB Output is correct
10 Correct 37 ms 2892 KB Output is correct
11 Correct 227 ms 14376 KB Output is correct
12 Correct 210 ms 8348 KB Output is correct
13 Correct 218 ms 10140 KB Output is correct
14 Correct 201 ms 7584 KB Output is correct
15 Correct 208 ms 8612 KB Output is correct
16 Correct 214 ms 8380 KB Output is correct
17 Correct 244 ms 12100 KB Output is correct
18 Correct 234 ms 12024 KB Output is correct
19 Correct 237 ms 12040 KB Output is correct
20 Correct 224 ms 14588 KB Output is correct