Submission #1118616

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118616		stefanneagu	Bridges (APIO19_bridges)	C++17	59 / 100	3051 ms	10928 KiB

bridges

#include <bits/stdc++.h>

using namespace std;

const int nmax = 1e5 + 1;

int nra = 1;
int bit[nmax];

int n, m;
int root[nmax], sz[nmax];
int mr[nmax], ms[nmax];

struct DSU {

  void init() {
    for(int i = 1; i <= n; i++) {
      root[i] = i;
      sz[i] = 1;
    }
  }

  int find(int a) {
    if(root[a] == a) {
      return a;
    }
    return root[a] = find(root[a]);
  }

  void unite(int a, int b) {
    if(a == b) {
      return;
    }
    if(sz[a] > sz[b]) {
      swap(a, b);
    }
    root[a] = b;
    sz[b] += sz[a];
  }

  int mfind(int a) {
    if(bit[a] != nra) {
      bit[a] = nra;
      mr[a] = find(a);
      ms[a] = sz[find(a)];
      // cout << "? " << a << " " << mr[a] << " " << ms[a] << '\n';
    }
    if(mr[a] == a) {
      return a;
    }
    return mr[a] = mfind(mr[a]);
  }

  void munite(int a, int b) {
    if(a == b) {
      return;
    }
    if(ms[a] > ms[b]) {
      swap(a, b);
    }
    mr[a] = b;
    ms[b] += ms[a];
  }
};

struct str {
	int a, b, c;
};

struct special {
  int t, a, b, c;
};

vector<str> qry, upd, edges;
int ans[nmax], mark[nmax];
int pas = 1;

bool cmp(special x, special y) {
  if(x.c != y.c) {
    return x.c > y.c;
  }
  return x.t < y.t;
}

bool cmp2(str x, str y) {
  return x.c < y.c;
}

void solve() {
  // cout << "START\n";
	vector<special> curr;
	vector<pair<int, int>> unsafe;
	for(int i = 1; i <= m; i++) {
    if(mark[i] != pas) {
      curr.push_back({0, edges[i].a, edges[i].b, edges[i].c});
    } else {
      // cout << "unsafe: " << edges[i].a << " " << edges[i].b << '\n';
      unsafe.push_back({i, edges[i].c});
    }
	}
	for(auto it : qry) {
    curr.push_back({1, it.a, it.c, it.b});
	}
	sort(curr.begin(), curr.end(), cmp);
	DSU ds;
	ds.init();
	for(auto _ : curr) {
    int t = _.t, a = _.a, b = _.b, c = _.c;
    // cout << "! " << t << " " << a << " " << b << " " << c << '\n';
    if(t == 0) {
      // unite
      ds.unite(ds.find(a), ds.find(b));
    } else {
      swap(b, c);
      // query
      for(auto it : upd) {
        if(it.c <= c) {
          edges[it.a].c = it.b;
        }
      }
      for(auto it : unsafe) {
        if(edges[it.first].c >= b) {
          // cout << "xtra: " << edges[it.first].a << " " << edges[it.first].b << '\n';
          ds.munite(ds.mfind(edges[it.first].a), ds.mfind(edges[it.first].b));
        }
        edges[it.first].c = it.second;
      }
      ans[c] = ms[ds.mfind(a)];
      nra++;
      // cout << ans[c] << '\n';
    }
	}
  // cout << "__\n";
  pas++;
  sort(upd.begin(), upd.end(), cmp2);
  for(auto it : upd) {
    edges[it.a].c = it.b;
  }
}

int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n >> m;
  edges.push_back({-1, -1, -1});
  for(int i = 1; i <= m; i++) {
    int a, b, c;
		cin >> a >> b >> c;
		if(a > b) {
			swap(a, b);
		}
		edges.push_back({a, b, c});
  }
  int q;
  cin >> q;
  int block = sqrt(q);
  for(int i = 1; i <= q; i++) {
    int t, a, b;
		cin >> t >> a >> b;
		if(t == 1) {
			// update
			mark[a] = pas;
			// cout << ">>" << a << " " << edges[a].a << " " << edges[a].b << "\n";
			upd.push_back({a, b, i});
		} else {
			// query
			qry.push_back({a, b, i});
		}
		if(i % block == 0 || i == q) {
			solve();
			upd.clear();
			qry.clear();
		}
  }
  for(int i = 1; i <= q; i++) {
    if(ans[i] != 0) {
      cout << ans[i] << "\n";
		}
  }
  return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 0 / 14
• Subtask 5: 13 / 13
• Subtask 6: 0 / 27