• [POI2011]Meteors


    嘟嘟嘟


    做了几道题之后,对整体二分有点感觉了。


    整体二分的本质就是二分答案。所以这道题二分的就是次数。
    然后就是套路了,把小于(mid)的操作都添加减去,然后查询,如果查询的值(x)比给定值大,就把这个询问放到左区间,否则减去(x),放到右区间。
    具体的操作,要支持区间加和单点查,第一反应是线段树,结果有两个点TLE的很惨。所以改成了树状数组差分维护前缀和,竟然过了,而且还跑的特别块。常数真是致命啊……

    #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 = 3e5 + 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, k, val[maxn];
    vector<int> con[maxn];
    struct Node
    {
      int L, R, w, id;
    }t[maxn << 1], tl[maxn << 1], tr[maxn << 1];
    int ans[maxn];
    
    ll c[maxn];
    int lowbit(int x) {return x & -x;}
    inline void clear(int pos)
    {
      for(; pos <= m; pos += lowbit(pos))
        if(c[pos]) c[pos] = 0;
        else break;
    }
    inline void add(int pos, int d)
    {
      if(!pos) return;
      for(; pos <= m; pos += lowbit(pos)) c[pos] += d;
    }
    inline ll query(int pos)
    {
      ll ret = 0;
      for(; pos; pos -= lowbit(pos)) ret += c[pos];
      return ret;
    }
    
    inline void Change(Node q)
    {
      if(q.L > q.R) add(q.L, q.w), add(1, q.w), add(q.R + 1, -q.w);
      else add(q.L, q.w), add(q.R + 1, -q.w);
    }
    inline void Clear(Node q)
    {
      if(q.L > q.R) clear(q.L), clear(1), clear(q.R + 1);
      else clear(q.L), clear(q.R + 1);
    }
    
    inline void solve(int kl, int kr, int ql, int qr)
    {
      if(ql > qr) return;
      if(kl == kr)
        {
          for(int i = ql; i <= qr; ++i)
    	if(t[i].id > k + 1) ans[t[i].id - k - 1] = kl;
          return;
        }
      int mid = (kl + kr) >> 1, id1 = 0, id2 = 0;
      for(int i = ql; i <= qr; ++i)
        {
          if(t[i].id <= k + 1)
    	{
    	  if(t[i].id <= mid) Change(t[i]), tl[++id1] = t[i];
    	  else tr[++id2] = t[i];
    	}
          else
    	{
    	  ll tot = 0; int x = t[i].id - k - 1;
    	  for(int j = 0; j < (int)con[x].size(); ++j)
    	    if((tot += query(con[x][j])) >= t[i].w) break;
    	  if(tot >= t[i].w) tl[++id1] = t[i];
    	  else t[i].w -= tot, tr[++id2] = t[i];
    	}
        }
      for(int i = 1; i <= id1; ++i) if(tl[i].id <= k + 1 && tl[i].id <= mid) Clear(tl[i]);
      for(int i = 1; i <= id1; ++i) t[ql + i - 1] = tl[i];
      for(int i = 1; i <= id2; ++i) t[ql + id1 + i - 1] = tr[i];
      solve(kl, mid, ql, ql + id1 - 1);
      solve(mid + 1, kr, ql + id1, qr);
    }
    
    int main()
    {
      n = read(); m = read();
      for(int i = 1, x; i <= m; ++i) x = read(), con[x].push_back(i);
      for(int i = 1; i <= n; ++i) val[i] = read();
      k = read();
      for(int i = 1; i <= k; ++i)
          t[i].L = read(), t[i].R = read(), t[i].w = read(), t[i].id = i;
      t[k + 1] = (Node){1, m, INF, k + 1};
      for(int i = 1; i <= n; ++i) t[k + 1 + i] = (Node){0, 0, val[i], k + 1 + i};
      solve(1, k + 1, 1, k + n + 1);
      for(int i = 1; i <= n; ++i)
        if(ans[i] > k) puts("NIE");
        else write(ans[i]), enter;
      return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/mrclr/p/10145180.html
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