【CF】220B Little Elephant and Array

区间动态统计的好题。

  1 /*  */
  2 #include <iostream>
  3 #include <string>
  4 #include <map>
  5 #include <queue>
  6 #include <set>
  7 #include <stack>
  8 #include <vector>
  9 #include <deque>
 10 #include <algorithm>
 11 #include <cstdio>
 12 #include <cmath>
 13 #include <ctime>
 14 #include <cstring>
 15 #include <climits>
 16 #include <cctype>
 17 #include <cassert>
 18 #include <functional>
 19 using namespace std;
 20 //#pragma comment(linker,"/STACK:102400000,1024000")
 21
 22 #define rep(i, a, n)     for (int i=a;i<n;++i)
 23 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 24 #define pb                 push_back
 25 #define mp                 make_pair
 26 #define all(x)             (x).begin(),(x).end()
 27 #define SZ(x)             ((int)(x).size())
 28 #define lson            l, mid, rt<<1
 29 #define rson            mid+1, r, rt<<1|1
 30
 31 typedef struct inter_t {
 32     int l, r, id, ans;
 33     inter_t() {}
 34     inter_t(int _l, int _r, int _id, int _ans=0):
 35         l(_l), r(_r), id(_id), ans(_ans) {}
 36     friend bool operator< (const inter_t& a, const inter_t& b) {
 37         if (a.r == b.r)
 38             return a.l > b.l;
 39         else
 40             return a.r < b.r;
 41     }
 42 } inter_t;
 43
 44 const int maxn = 1e5+5;
 45 vector<int> vc[maxn];
 46 int sz[maxn];
 47 vector<inter_t> Q;
 48 map<int,int> tb;
 49 int d[maxn];
 50 int a[maxn], l = 1;
 51 int v[maxn];
 52
 53 bool comp(const inter_t& a, const inter_t& b) {
 54     return a.id < b.id;
 55 }
 56
 57 int main() {
 58     int i, j, k;
 59     int n, m;
 60
 61     #ifndef ONLINE_JUDGE
 62         freopen("data.in", "r", stdin);
 63         freopen("data.out", "w", stdout);
 64     #endif
 65
 66     scanf("%d %d", &n, &m);
 67     for (i=1; i<=n; ++i)
 68         scanf("%d", &a[i]);
 69
 70     int li, ri;
 71     for (i=0; i<m; ++i) {
 72         scanf("%d %d", &li, &ri);
 73         Q.push_back(inter_t(li, ri, i));
 74     }
 75     sort(Q.begin(), Q.end());
 76     Q.push_back(inter_t(0,n+1,m));
 77     memset(d, 0, sizeof(d));
 78     memset(sz, 0, sizeof(sz));
 79
 80     int r = 1, mr, x, id, p, cnt;
 81     i = 0;
 82     while (i < m) {
 83         mr = Q[i].r;
 84         while (r <= mr) {
 85             x = a[r];
 86             id = tb[x];
 87             if (id == 0) {
 88                 tb[x] = id = l;
 89                 l++;
 90                 v[l] = x;
 91             }
 92             vc[id].push_back(r);
 93             ++sz[id];
 94             if (sz[id] >= x) {
 95                 p = vc[id][sz[id]-x];
 96                 ++d[p];
 97             }
 98             if (sz[id] >= x+1) {
 99                 p = vc[id][sz[id]-x-1];
100                 d[p] -= 2;
101             }
102             if (sz[id] > x+1) {
103                 p = vc[id][sz[id]-x-2];
104                 ++d[p];
105             }
106             ++r;
107         }
108         cnt = 0;
109         k = mr+1;
110         while (Q[i].r == mr) {
111             for (j=Q[i].l; j<k; ++j)
112                 cnt += d[j];
113             Q[i].ans = cnt;
114             k = Q[i].l;
115             ++i;
116         }
117     }
118
119     sort(Q.begin(), Q.end(), comp);
120     for (i=0; i<m; ++i)
121         printf("%d\n", Q[i].ans);
122
123     #ifndef ONLINE_JUDGE
124         printf("time = %d.\n", (int)clock());
125     #endif
126
127     return 0;
128 }