Submission #1098306

#	Time	Username	Problem	Language	Result	Execution time	Memory
1098306		Zero_OP	Spring cleaning (CEOI20_cleaning)	C++14	100 / 100	166 ms	20176 KiB

cleaning

#include <bits/stdc++.h>

using namespace std;

#define dbg(x) "[" #x " = " << (x) << "]"

const int MAX = 1e5 + 5;

int n, q, timerHLD, root, parent[MAX], heavy[MAX], sz[MAX], depth[MAX], head[MAX], posHLD[MAX];
vector<int> adj[MAX];
bool original_is_leaf[MAX], is_leaf[MAX];

void predfs(int u, int pre){
    sz[u] = 1;
    for(int v : adj[u]) if(v != pre){
        depth[v] = depth[u] + 1;
        parent[v] = u;
        predfs(v, u);
        sz[u] += sz[v];
        if(heavy[u] == 0 || sz[heavy[u]] < sz[v]){
            heavy[u] = v;
        }
    }
}

void dfsHLD(int u, int hd){
    head[u] = hd;
    posHLD[u] = ++timerHLD;
    if(heavy[u] != 0){
        dfsHLD(heavy[u], hd);
        for(int v : adj[u]){
            if(v != parent[u] && v != heavy[u]){
                dfsHLD(v, v);
            }
        }
    }
}

struct SegmentTree{
    vector<int> st, lazy;

    SegmentTree(int n) : st(n << 2), lazy(n << 2) {}

    void build(int id, int l, int r){
        st[id] = r - l + 1;
        if(l < r){
            int mid = l + r >> 1;
            build(id << 1, l, mid);
            build(id << 1 | 1, mid + 1, r);
            st[id] = st[id << 1] + st[id << 1 | 1];
        }
    }

    void flip(int id, int l, int r){
        st[id] = (r - l + 1) - st[id];
        lazy[id] ^= 1;
    }

    void lazyDown(int id, int l, int r, int mid){
        if(lazy[id] > 0){
            flip(id << 1, l, mid);
            flip(id << 1 | 1, mid + 1, r);
            lazy[id] = 0;
        }
    }

    void pull(int id){
        st[id] = st[id << 1] + st[id << 1 | 1];
    }

    void update(int id, int l, int r, int u, int v){
        if(u <= l && r <= v){
            flip(id, l, r);
        } else{
            int mid = l + r >> 1;
            lazyDown(id, l, r, mid);
            if(u <= mid) update(id << 1, l, mid, u, v);
            if(mid < v) update(id << 1 | 1, mid + 1, r, u, v);
            pull(id);
        }
    }

    int getFilled(){
        return st[1];
    }
};

void toggle(int u, SegmentTree& T){
    while(u > 0){
        T.update(1, 1, n, posHLD[head[u]], posHLD[u]);
        u = parent[head[u]];
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    #define filename "task"
    if(fopen(filename".inp", "r")){
        freopen(filename".inp", "r", stdin);
        freopen(filename".out", "w", stdout);
    }

    cin >> n >> q;
    for(int i = 1; i < n; ++i){
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    for(int i = 1; i <= n; ++i){
        if((int)adj[i].size() > 1){
            root = i;
            break;
        }
    }

    predfs(root, -1);
    dfsHLD(root, root);
    SegmentTree T(n);
    T.build(1, 1, n);

    int numLeaves = 0;
    for(int i = 1; i <= n; ++i){
        if((int)adj[i].size() == 1){
            original_is_leaf[i] = true;
            ++numLeaves;
            toggle(i, T);
        }
    }

    copy(original_is_leaf + 1, original_is_leaf + 1 + n, is_leaf + 1);
    int original_numLeaves = numLeaves;

    while(q--){
        vector<int> roll;
        int D;
        cin >> D;
        vector<int> nodes(D);
        for(int i = 0; i < D; ++i){
            cin >> nodes[i];
            if(is_leaf[nodes[i]]){
                is_leaf[nodes[i]] = false;
            } else{
                toggle(nodes[i], T);
                ++numLeaves;
                roll.push_back(nodes[i]);
            }
        }

        if(numLeaves & 1){
            cout << -1 << '\n';
        } else{
            cout << n + D + T.getFilled() - 2 << '\n';
        }

        numLeaves = original_numLeaves;
        for(int u : nodes){
            is_leaf[u] = original_is_leaf[u];
        }

        while(!roll.empty()){
            toggle(roll.back(), T);
            roll.pop_back();
        }
    }
}

Compilation message (stderr)

cleaning.cpp: In member function 'void SegmentTree::build(int, int, int)':
cleaning.cpp:47:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   47 |             int mid = l + r >> 1;
      |                       ~~^~~
cleaning.cpp: In member function 'void SegmentTree::update(int, int, int, int, int)':
cleaning.cpp:75:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   75 |             int mid = l + r >> 1;
      |                       ~~^~~
cleaning.cpp: In function 'int main()':
cleaning.cpp:101:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         freopen(filename".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:102:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen(filename".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 17 / 17
• Subtask 7: 30 / 30