Submission #90464

#	Time	Username	Problem	Language	Result	Execution time	Memory
90464		popovicirobert	Special graph (IZhO13_specialg)	C++14	0 / 100	13 ms	12024 KiB

specialg

#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
#define ld long double
// 217
// 44

using namespace std;

const int MAXN = (int) 1e5;

int nxt[MAXN + 1];

struct Fenwick {
    vector <int> arr;
    int n;
    inline void init(int _n) {
        n = _n;
        arr.resize(n + 1);
    }
    inline void update(int pos, int val) {
        for(int i = pos; i <= n; i += lsb(i)) {
            arr[i] += val;
        }
    }
    inline int query(int pos) {
        int ans = 0;
        for(int i = pos; i > 0; i -= lsb(i)) {
            ans += arr[i];
        }
        return ans;
    }
    inline int sum(int l, int r) {
        return query(r) - query(l - 1);
    }
}aib_cyc;

Fenwick aib[MAXN + 1];

bool vis[MAXN + 1];

inline void get_cycle(vector <int> &cycle) {
    int nod = 1;
    vector <int> nodes;
    while(vis[nod] == 0) {
        nodes.push_back(nod);
        vis[nod] = 1;
        nod = nxt[nod];
    }
    reverse(nodes.begin(), nodes.end());
    while(nodes.back() != nod) {
        nodes.pop_back();
    }
    swap(nodes, cycle);
    cycle.push_back(0);
    reverse(cycle.begin(), cycle.end());
    memset(vis, 0, sizeof(vis));
}

bool in_cyc[MAXN + 1];
int pos[MAXN + 1], id[MAXN + 1];

vector <int> g[MAXN + 1];
int first[MAXN + 1], last[MAXN + 1];
int sz[MAXN + 1], lvl[MAXN + 1];

void dfs(int nod, int x) {
    first[nod] = ++sz[x];
    id[nod] = x;
    for(auto it : g[nod]) {
        lvl[it] = lvl[nod] + 1;
        dfs(it, x);
    }
    last[nod] = ++sz[x];
}

inline int solve_cyc_cyc(int a, int b) {
    if(pos[a] <= pos[b]) {
        if(aib_cyc.sum(pos[a], pos[b] - 1) == 0) {
            return pos[b] - pos[a];
        }
        return -1;
    }
    if(aib_cyc.sum(pos[a], aib_cyc.n) + aib_cyc.sum(1, pos[b]) == 0) {
        return aib_cyc.n - pos[a] + pos[b];
    }
    return -1;
}

inline int solve_tree_tree(int a, int b, bool t) {
    if(id[a] != id[b]) {
        return -1;
    }
    if(first[b] <= first[a] && last[a] <= last[b] && aib[id[a]].sum(first[b] + t, first[a]) == 0) {
        return lvl[a] - lvl[b];
    }
    return -1;
}

inline int solve_tree_cyc(int a, int b) {
    if(solve_cyc_cyc(nxt[id[a]], b) == -1 || solve_tree_tree(a, id[a], 0) == -1) {
        return -1;
    }
    return solve_cyc_cyc(nxt[id[a]], b) + solve_tree_tree(a, id[a], 0) + 1;
}

int main() {
    //ifstream cin("A.in");
    //ofstream cout("A.out");
    int i, n, m;
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    cin >> n;
    for(i = 1; i <= n; i++) {
        cin >> nxt[i];
    }
    vector <int> cycle;
    get_cycle(cycle);
    int cyc_sz = (int) cycle.size() - 1;
    for(i = 1; i <= cyc_sz; i++) {
        id[cycle[i]] = cycle[i];
        pos[cycle[i]] = i;
        vis[cycle[i]] = 1;
        in_cyc[cycle[i]] = 1;
    }
    for(i = 1; i <= n; i++) {
        if(vis[nxt[i]] == 0 && vis[i] == 0) {
            g[nxt[i]].push_back(i);
        }
    }
    for(i = 1; i <= n; i++) {
        if(vis[nxt[i]] == 1 && vis[i] == 0) {
            dfs(i, i);
        }
    }
    aib_cyc.init(cyc_sz);
    for(i = 1; i <= n; i++) {
        aib[i].init(sz[i]);
    }
    cin >> m;
    while(m > 0) {
        m--;
        int type, a, b;
        cin >> type >> a;
        if(type == 1) {
            if(in_cyc[a]) {
                aib_cyc.update(pos[a], 1);
            }
            else {
                aib[id[a]].update(first[a], 1);
                aib[id[a]].update(last[a], -1);
            }
        }
        else {
            cin >> b;
            int ans = -1;
            if(in_cyc[a] && in_cyc[b]) {
                ans = solve_cyc_cyc(a, b);
            }
            else if(!in_cyc[a] && !in_cyc[b]) {
                ans = solve_tree_tree(a, b, 1);
            }
            else if(in_cyc[b]) {
                ans = solve_tree_cyc(a, b);
            }
            cout << ans << "\n";
        }
    }
    //cin.close();
    //cout.close();
    return 0;
}

• Subtask 1: 0 / 100