BZOJ3524 [POI2014] Couriers

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cstring>
 5 #define rep(i,l,r) for(int i=l; i<=r; i++)
 6 #define clr(x,y) memset(x,y,sizeof(x))
 7 #define travel(x) for(Edge *p=last[x]; p; p=p->pre)
 8 using namespace std;
 9 const int INF = 0x3f3f3f3f;
10 const int maxn = 500010;
11 int n,m,x,y,tot=0,a[maxn],root[maxn],ls[maxn*20],rs[maxn*20],sum[maxn*20];
12 inline int read(){
13     int ans = 0, f = 1;
14     char c = getchar();
15     while (!isdigit(c)){
16         if (c == ‘-‘) f = -1;
17         c = getchar();
18     }
19     while (isdigit(c)){
20         ans = ans * 10 + c - ‘0‘;
21         c = getchar();
22     }
23     return ans * f;
24 }
25 void insert(int l,int r,int x,int &y,int v){
26     y = ++tot;
27     sum[y] = sum[x] + 1;
28     if (l == r) return;
29     ls[y] = ls[x]; rs[y] = rs[x];
30     int mid = (l + r) >> 1;
31     if (v <= mid) insert(l,mid,ls[x],ls[y],v);
32     else insert(mid+1,r,rs[x],rs[y],v);
33 }
34 inline void query(int x,int y){
35     int l=1,r=n,a=root[y],b=root[x-1];
36     while (l < r){
37         int mid = (l + r) >> 1;
38         if (sum[ls[a]] - sum[ls[b]] > sum[rs[a]] - sum[rs[b]]){
39             a = ls[a]; b = ls[b]; r = mid;
40         }
41         else{
42             a = rs[a]; b = rs[b]; l = mid + 1;
43         }
44     }
45     if (sum[a] - sum[b] > (y - x + 1) >> 1) printf("%d\n",l);
46     else printf("0\n");
47 }
48 int main(){
49     n = read(); m = read();
50     rep(i,1,n) a[i] = read();
51     rep(i,1,n) insert(1,n,root[i-1],root[i],a[i]);
52     rep(i,1,m){
53         x = read(); y = read();
54         query(x,y);
55     }
56     return 0;
57 }