【CF】220B Little Elephant and Array

区间动态统计的好题。

 /*  */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define pb                 push_back
 #define mp                 make_pair
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 typedef struct inter_t {
     int l, r, id, ans;
     inter_t() {}
     inter_t(int _l, int _r, int _id, int _ans=):
         l(_l), r(_r), id(_id), ans(_ans) {}
     friend bool operator< (const inter_t& a, const inter_t& b) {
         if (a.r == b.r)
             return a.l > b.l;
         else
             return a.r < b.r;
     }
 } inter_t;

 const int maxn = 1e5+;
 vector<int> vc[maxn];
 int sz[maxn];
 vector<inter_t> Q;
 map<int,int> tb;
 int d[maxn];
 int a[maxn], l = ;
 int v[maxn];

 bool comp(const inter_t& a, const inter_t& b) {
     return a.id < b.id;
 }

 int main() {
     int i, j, k;
     int n, m;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     scanf("%d %d", &n, &m);
     for (i=; i<=n; ++i)
         scanf("%d", &a[i]);

     int li, ri;
     for (i=; i<m; ++i) {
         scanf("%d %d", &li, &ri);
         Q.push_back(inter_t(li, ri, i));
     }
     sort(Q.begin(), Q.end());
     Q.push_back(inter_t(,n+,m));
     memset(d, , sizeof(d));
     memset(sz, , sizeof(sz));

     int r = , mr, x, id, p, cnt;
     i = ;
     while (i < m) {
         mr = Q[i].r;
         while (r <= mr) {
             x = a[r];
             id = tb[x];
             if (id == ) {
                 tb[x] = id = l;
                 l++;
                 v[l] = x;
             }
             vc[id].push_back(r);
             ++sz[id];
             if (sz[id] >= x) {
                 p = vc[id][sz[id]-x];
                 ++d[p];
             }
             if (sz[id] >= x+) {
                 p = vc[id][sz[id]-x-];
                 d[p] -= ;
             }
             if (sz[id] > x+) {
                 p = vc[id][sz[id]-x-];
                 ++d[p];
             }
             ++r;
         }
         cnt = ;
         k = mr+;
         while (Q[i].r == mr) {
             for (j=Q[i].l; j<k; ++j)
                 cnt += d[j];
             Q[i].ans = cnt;
             k = Q[i].l;
             ++i;
         }
     }

     sort(Q.begin(), Q.end(), comp);
     for (i=; i<m; ++i)
         printf("%d\n", Q[i].ans);

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }