HDU - 4417 Super Mario(分块+二分)

将给定区间分块，将每个块从小到大排序，二分查询每个块，

#include<bits/stdc++.h>

#define mem(a,b) memset(a,b,sizeof(a))
#define sc(x) scanf("%d",&(x))

using namespace std;

const int maxn=1e5+10;

int block,mub,l[maxn],r[maxn],belong[maxn];

int arr[maxn],n,m,tt[maxn];

void built()
{
    block=sqrt(n);
    mub=n/block;if(n%mub) mub++;
    for(int i=1;i<=mub;i++)
        l[i]=(i-1)*block+1,r[i]=i*block;
    r[mub]=n;
    for(int i=1;i<=n;i++)
        belong[i]=(i-1)/block+1;
    for(int i=1;i<=n;i++)
        sort(tt+l[belong[i]],tt+1+r[belong[i]]);
}

int query(int a,int b,int c)
{
    int ans=0;
    if(belong[a]==belong[b])
    {
        for(int i=a;i<=b;i++)
            if(arr[i]<=c) ans++;
    }
    else
    {
        for(int i=a;i<=r[belong[a]];i++)
            if(arr[i]<=c) ans++;
        for(int i=belong[a]+1;i<belong[b];i++)
            ans+=upper_bound(tt+l[i],tt+r[i]+1,c)-tt-l[i];
        for(int i=l[belong[b]];i<=b;i++)
            if(arr[i]<=c) ans++;
    }
    return ans;
}

int main(){
    int t;
    sc(t);
    for(int ii=1;ii<=t;ii++)
    {
        sc(n),sc(m);
        for(int i=1;i<=n;i++)
        {
            sc(arr[i]);
            tt[i]=arr[i];
        }
        built();
        printf("Case %d:\n",ii);
        while(m--)
        {
            int l,r,c;
            sc(l),sc(r),sc(c);
            l++,r++;
            printf("%d\n",query(l,r,c));
        }
    }
    return 0;
}