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  • P5443 [APIO2019]桥梁 [分块+并查集]

    分块+并查集,大板子,没了。
    并查集不路径压缩,可撤销,然后暴力删除
    这样对于每个块都是独立的,所以直接搞就行了。
    然后块内修改操作搞掉,就是单独的了

    // powered by c++11
    // by Isaunoya
    #include <bits/stdc++.h>
    #define rep(i, x, y) for (register int i = (x); i <= (y); ++i)
    #define Rep(i, x, y) for (register int i = (x); i >= (y); --i)
    using namespace std;
    using db = double;
    using ll = long long;
    using uint = unsigned int;
    // #define int long long
    using pii = pair<int, int>;
    #define ve vector
    #define Tp template
    #define all(v) v.begin(), v.end()
    #define sz(v) ((int)v.size())
    #define pb emplace_back
    #define fir first
    #define sec second
    // the cmin && cmax
    Tp<class T> void cmax(T& x, const T& y) {
      if (x < y) x = y;
    }
    Tp<class T> void cmin(T& x, const T& y) {
      if (x > y) x = y;
    }
    // sort , unique , reverse
    Tp<class T> void sort(ve<T>& v) { sort(all(v)); }
    Tp<class T> void unique(ve<T>& v) {
      sort(all(v));
      v.erase(unique(all(v)), v.end());
    }
    Tp<class T> void reverse(ve<T>& v) { reverse(all(v)); }
    const int SZ = 0x191981;
    struct FILEIN {
      ~FILEIN() {}
      char qwq[SZ], *S = qwq, *T = qwq, ch;
      char GETC() { return (S == T) && (T = (S = qwq) + fread(qwq, 1, SZ, stdin), S == T) ? EOF : *S++; }
      FILEIN& operator>>(char& c) {
        while (isspace(c = GETC()))
          ;
        return *this;
      }
      FILEIN& operator>>(string& s) {
        while (isspace(ch = GETC()))
          ;
        s = ch;
        while (!isspace(ch = GETC())) s += ch;
        return *this;
      }
      Tp<class T> void read(T& x) {
        bool sign = 1;
        while ((ch = GETC()) < 0x30)
          if (ch == 0x2d) sign = 0;
        x = (ch ^ 0x30);
        while ((ch = GETC()) > 0x2f) x = x * 0xa + (ch ^ 0x30);
        x = sign ? x : -x;
      }
      FILEIN& operator>>(int& x) { return read(x), *this; }
      // FILEIN& operator>>(signed& x) { return read(x), *this; }
      FILEIN& operator>>(unsigned& x) { return read(x), *this; }
    } in;
    struct FILEOUT {
      const static int LIMIT = 0x114514;
      char quq[SZ], ST[0x114];
      signed sz, O;
      ~FILEOUT() { flush(); }
      void flush() {
        fwrite(quq, 1, O, stdout);
        fflush(stdout);
        O = 0;
      }
      FILEOUT& operator<<(char c) { return quq[O++] = c, *this; }
      FILEOUT& operator<<(string str) {
        if (O > LIMIT) flush();
        for (char c : str) quq[O++] = c;
        return *this;
      }
      Tp<class T> void write(T x) {
        if (O > LIMIT) flush();
        if (x < 0) {
          quq[O++] = 0x2d;
          x = -x;
        }
        do {
          ST[++sz] = x % 0xa ^ 0x30;
          x /= 0xa;
        } while (x);
        while (sz) quq[O++] = ST[sz--];
        return;
      }
      FILEOUT& operator<<(int x) { return write(x), *this; }
      // FILEOUT& operator<<(signed x) { return write(x), *this; }
      FILEOUT& operator<<(unsigned x) { return write(x), *this; }
    } out;
    
    const int maxn = 2e5 + 52;
    int n, m, num = 0;
    int q, len, ans[maxn];
    bool vis[maxn], used[maxn];
    vector<int> b;
    struct Edge {
      int u, v, w;
    } e[maxn];
    struct Que {
      int op, x, y;
    } Q[maxn];
    struct Qry {
      int id, u, v, w;
      bool operator<(const Qry& other) const {
        if (w != other.w) return w > other.w;
        return id < other.id;
      }
    };
    vector<Qry> qr;
    struct DSU {
      int n, fa[maxn], sz[maxn], top, sta[maxn], stb[maxn];
      inline void reset(int _n) {
        n = _n, top = 0;
        for (int i = 1; i <= n; i++) sz[fa[i] = i] = 1;
      }
      inline void reset() {
        while (top) {
          int u = sta[top], v = stb[top];
          sz[u] -= sz[v], fa[v] = v;
          top--;
        }
      }
      inline int find(int x) { return x == fa[x] ? x : find(fa[x]); }
      inline int getsize(int x) {
        int fx = find(x);
        return sz[fx];
      }
      inline void merge(int u, int v, int r) {
        if ((u = find(u)) == (v = find(v))) return;
        if (sz[u] < sz[v]) u ^= v ^= u ^= v;
        sz[u] += sz[v], fa[v] = u;
        if (r) sta[++top] = u, stb[top] = v;
      }
    } dsu;
    inline void solve(int l, int r) {
      dsu.reset(n);
      b.clear(), qr.clear();
      for (int i = 1; i <= m; i++) {
        used[i] = 0;
      }
      for (int i = l; i <= r; i++) {
        if (Q[i].op == 1) {
          used[Q[i].x] = 1;
        } else {
          qr.push_back({ ++q, Q[i].x, i, Q[i].y });
        }
      }
      for (int i = 1; i <= m; i++)
        if (!used[i])
          qr.push_back({ -1, e[i].u, e[i].v, e[i].w });
        else
          b.push_back(i);
      sort(qr.begin(), qr.end());
      for (auto x : qr) {
        if (x.id == -1) {
          dsu.merge(x.u, x.v, 0);
          continue;
        }
        for (int i = x.v; i >= l; i--) {
          if (Q[i].op == 1) {
            if (!vis[Q[i].x]) {
              vis[Q[i].x] = 1;
              if (Q[i].y >= x.w) {
                dsu.merge(e[Q[i].x].u, e[Q[i].x].v, 1);
              }
            }
          }
        }
        for (auto y : b) {
          if (!vis[y] && e[y].w >= x.w) {
            dsu.merge(e[y].u, e[y].v, 1);
          }
        }
        ans[x.id] = dsu.getsize(x.u);
        for (auto y : b) {
          vis[y] = 0;
        }
        dsu.reset();
      }
      for (int i = l; i <= r; i++) {
        if (Q[i].op == 1) {
          e[Q[i].x].w = Q[i].y;
        }
      }
    }
    signed main() {
    #ifdef _WIN64
      freopen("testdata.in", "r", stdin);
    #else
      ios_base ::sync_with_stdio(false);
      cin.tie(nullptr), cout.tie(nullptr);
    #endif
      // code begin.
      in >> n >> m;
      for (int i = 1; i <= m; i++) {
        int u, v, w;
        in >> u >> v >> w;
        e[i] = { u, v, w };
      }
      in >> num;
      len = 900;
      for (int i = 1; i <= num; i++) {
        in >> Q[i].op >> Q[i].x >> Q[i].y;
      }
      for (int i = 1; i <= num; i += len) solve(i, min(num, i + len - 1));
      for (int i = 1; i <= q; i++) out << ans[i] << '
    ';
      return 0;
      // code end.
    }
    
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  • 原文地址:https://www.cnblogs.com/Isaunoya/p/12310916.html
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