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  • [SDOI2009]HH的项链(莫队)

    嘟嘟嘟


    这题原本莫队能过,自从某谷加强数据后好像就只能80了。
    但这并不重要。
    (其实写这篇博客只是想记录一下莫队板子)


    莫队,总而言之,离线,排序,暴力。

    #include<cstdio>
    #include<iostream>
    #include<cmath>
    #include<algorithm>
    #include<cstring>
    #include<cstdlib>
    #include<cctype>
    #include<vector>
    #include<stack>
    #include<queue>
    using namespace std;
    #define enter puts("") 
    #define space putchar(' ')
    #define Mem(a, x) memset(a, x, sizeof(a))
    #define rg register
    typedef long long ll;
    typedef double db;
    const int INF = 0x3f3f3f3f;
    const db eps = 1e-8;
    const int maxn = 5e5 + 5;
    const int maxN = 1e6 + 5;
    inline ll read()
    {
      ll ans = 0;
      char ch = getchar(), last = ' ';
      while(!isdigit(ch)) last = ch, ch = getchar();
      while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
      if(last == '-') ans = -ans;
      return ans;
    }
    inline void write(ll x)
    {
      if(x < 0) x = -x, putchar('-');
      if(x >= 10) write(x / 10);
      putchar(x % 10 + '0');
    }
    
    int n, m, S, a[maxn];
    int tot[maxN], ans[maxn], cnt = 0;
    struct Node
    {
      int L, R, id, b;
      bool operator < (const Node& oth)const
      {
        return b < oth.b || (b == oth.b && R < oth.R);
      }
    }q[maxn];
    
    int main()
    {
      n = read(); S = sqrt(n);
      for(int i = 1; i <= n; ++i) a[i] = read();
      m = read();
      for(int i = 1, L, R; i <= m; ++i)
        {
          L = read(); R = read();
          q[i] = (Node){L, R, i, (L - 1) / S + 1};
        }
      sort(q + 1, q + m + 1);
      for(int i = 1, l = 0, r = 0; i <= m; ++i)
        {
          while(l < q[i].L) if(!--tot[a[l++]]) cnt--;
          while(l > q[i].L) if(!tot[a[--l]]++) cnt++;
          while(r < q[i].R) if(!tot[a[++r]]++) cnt++;
          while(r > q[i].R) if(!--tot[a[r--]]) cnt--;
          ans[q[i].id] = cnt;
        }
      for(int i = 1; i <= m; ++i) write(ans[i]), enter;
      return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/mrclr/p/10077153.html
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