Submission #622768

#	Time	Username	Problem	Language	Result	Execution time	Memory
622768		Do_you_copy	Bridges (APIO19_bridges)	C++17	100 / 100	2244 ms	16396 KiB

bridges

#include <bits/stdc++.h>
#define taskname "test"
#define fi first
#define se second
#define pb push_back
#define faster ios_base::sync_with_stdio(0); cin.tie(0);
using namespace std;
using ll = long long;
using ull = unsigned ll;
using ld = long double;
using pii = pair <int, int>;
using pil = pair <int, ll>;
using pli = pair <ll, int>;
using pll = pair <ll, ll>;
mt19937 Rand(chrono::steady_clock::now().time_since_epoch().count());

ll min(const ll &a, const ll &b){
    return (a < b) ? a : b;
}

ll max(const ll &a, const ll &b){
    return (a > b) ? a : b;
}

//const ll Mod = 1000000007;
//const ll Mod2 = 999999999989;
//only use when required
const int maxN = 2e5 + 10;
const int maxM = 2e5 + 10;
const int maxQ = 2e5 + 10;
const int SQRT = 1000;
int n, m, q;

struct TEdge{
    int u, v, w, idx;
};
TEdge e[maxM];

struct TQuery{
    int t, x, y;
};

TQuery query[maxQ];
struct TDSU{
    vector <pii> save;
    vector <int> lab;
    TDSU(){}
    TDSU(int _n){
        lab.resize(_n, -1);
    }
    inline void resize(int _n){
        lab.resize(_n, -1);
    }
    inline int find_set(int u){
        if (lab[u] < 0) return u;
        return lab[u] = find_set(lab[u]);
    }
    inline int find(int u){
        if (lab[u] < 0) return u;
        return find(lab[u]);
    }
    inline void merge(int u, int v){
        if (lab[u] > lab[v]) swap(u, v);
        save.pb({v, lab[v]});
        lab[u] += lab[v];
        lab[v] = u;
    }
    inline void undo(){

        int v = save.back().fi;
        int u = lab[v];
        lab[v] = save.back().se;
        lab[u] -= lab[v];
        save.pop_back();
    }
    inline void clear(){
        lab.clear();
        save.clear();
    }
    inline void reset(int _n){
        clear();
        resize(_n);
    }
    inline void roll_back(int _n){
        while (save.size() > _n) undo();
    }
};

TDSU dsu;

bool changed[maxM];
int ans[maxQ];
vector <int> join[maxQ];
void Init(){
    cin >> n >> m;
    for (int i = 1; i <= m; ++i){
        cin >> e[i].u >> e[i].v >> e[i].w;
        e[i].idx = i;
    }
    vector <int> block_idx;
    ll cnt = 0;
    block_idx.pb(0);
    cin >> q;
    for (int i = 1; i <= q; ++i){
        cin >> query[i].t >> query[i].x >> query[i].y;
        --query[i].t;
        ++cnt;
        if (cnt >= SQRT){
            block_idx.pb(i);
            cnt = 0;
        }
    }
    block_idx.pb(q);
    //cerr << q << " ";
    for (int _ = 0; _ < block_idx.size() - 1; ++_){
        int l = block_idx[_] + 1, r = block_idx[_ + 1];
        dsu.reset(n + 1);
        vector <int> ask, unchanged, unstable;
        for (int i = l; i <= r; ++i){
            if (query[i].t) ask.pb(i);
            else{
                changed[query[i].x] = 1;
                unstable.pb(i);
            }
        }
        for (int i = 1; i <= m; ++i){
            if (!changed[i]) unchanged.pb(i);
            else changed[i] = 0;
        }
        for (int i = l; i <= r; ++i){
            if (!query[i].t) e[query[i].x].w = query[i].y;
            else{
                join[i - l].clear();
                for (int j: unstable){
                    if (e[query[j].x].w >= query[i].y) join[i - l].pb(query[j].x);
                }
            }
        }
        sort(ask.begin(), ask.end(),[&](const int &i, const int &j){
            return query[i].y > query[j].y;
        });
        sort(unchanged.begin(), unchanged.end(),[&](const int &i, const int &j){
            return e[i].w > e[j].w;
        });
        int j = 0;
        for (int __ = 0; __ < ask.size(); ++__){
            int i = ask[__];
            while (j < unchanged.size() && e[unchanged[j]].w >= query[i].y){
                int x = dsu.find_set(e[unchanged[j]].u), y = dsu.find_set(e[unchanged[j]].v);
                if (x != y){
                    dsu.merge(x, y);
                }
                ++j;
            }
            int prev_sz = dsu.save.size();
            for (int jj: join[i - l]){
                int x = dsu.find(e[jj].u), y = dsu.find(e[jj].v);
                if (x != y){
                    dsu.merge(x, y);
                }
            }
            ans[i] = - dsu.lab[dsu.find(query[i].x)];
            dsu.roll_back(prev_sz);
        }
    }
    for (int i = 1; i <= q; ++i){
        if (query[i].t){
            cout << ans[i] << "\n";
            //cerr << ans[i] << "\n";
        }
    }
}


int main(){
    if (fopen(taskname".inp", "r")){
        freopen(taskname".inp", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }
    faster;
    ll tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
}

Compilation message (stderr)

bridges.cpp: In member function 'void TDSU::roll_back(int)':
bridges.cpp:85:28: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   85 |         while (save.size() > _n) undo();
      |                ~~~~~~~~~~~~^~~~
bridges.cpp: In function 'void Init()':
bridges.cpp:115:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  115 |     for (int _ = 0; _ < block_idx.size() - 1; ++_){
      |                     ~~^~~~~~~~~~~~~~~~~~~~~~
bridges.cpp:146:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  146 |         for (int __ = 0; __ < ask.size(); ++__){
      |                          ~~~^~~~~~~~~~~~
bridges.cpp:148:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  148 |             while (j < unchanged.size() && e[unchanged[j]].w >= query[i].y){
      |                    ~~^~~~~~~~~~~~~~~~~~
bridges.cpp: In function 'int main()':
bridges.cpp:177:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  177 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
bridges.cpp:178:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  178 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 14 / 14
• Subtask 5: 13 / 13
• Subtask 6: 27 / 27