hdu4417 Super Mario

题目：给你n个数，m个询问，形如(L,R,H)，让你输出区间[L,R]中小于等于H的数的数目

思路：主席树，查询的时候看一下区间往左走还是

#pragma comment(linker, "/STACK:1024000000,1024000000")#include<iostream>#include<algorithm>#include<cstdio>#include<cmath>#include<cstring>#include<string>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<list>#include<numeric>using namespace std;#define PI acos(-1.0)#define LL long long#define ULL unsigned long long#define INF 0x3f3f3f3f#define mm(a,b) memset(a,b,sizeof(a))#define PP puts("*********************");template<class T> T f_abs(T a){ return a > 0 ? a : -a; }template<class T> T gcd(T a, T b){ return b ? gcd(b, a%b) : a; }template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}// 0x3f3f3f3f3f3f3f3f// 0x3f3f3f3fconst int maxn=1e5+50;const int maxm=maxn*30;int arr[maxn];//原数组int num[2*maxn],siz;//num离散化之后的数组int root[maxn],lson[maxm],rson[maxm],cnt[maxm];//根节点，左儿子，右儿子，区间内的数出现次数的前缀和int tot;void init(){    tot=1;    root[0]=lson[0]=rson[0]=cnt[0]=0;//建一棵空树    sort(num+1,num+siz+1);//离散化    siz=unique(num+1,num+siz+1)-num-1;}int Hash(int x){    return lower_bound(num+1,num+siz+1,x)-num;}int update(int rt,int pos,int val){    int newrt=tot++,temp=newrt;    cnt[newrt]=cnt[rt]+val;    int l=1,r=siz;    while(l<r){        int mid=(l+r)/2;        if(pos<=mid){            r=mid;            lson[newrt]=tot++;rson[newrt]=rson[rt];            newrt=lson[newrt];rt=lson[rt];        }        else{            l=mid+1;            lson[newrt]=lson[rt];rson[newrt]=tot++;            newrt=rson[newrt];rt=rson[rt];        }        cnt[newrt]=cnt[rt]+val;    }    return temp;}int ans;void query(int left_rt,int right_rt,int k){    int l=1,r=siz;    while(l<r){        int mid=(l+r)/2;        int temp=cnt[lson[right_rt]]-cnt[lson[left_rt]];        if(k<=mid){            r=mid;            left_rt=lson[left_rt];            right_rt=lson[right_rt];        }        else{            l=mid+1;            ans+=temp;            left_rt=rson[left_rt];            right_rt=rson[right_rt];        }    }    ans+=cnt[right_rt]-cnt[left_rt];}int L[maxn],R[maxn],H[maxn];int main(){    int T,cas=0,n,m;    scanf("%d",&T);    while(T--){        scanf("%d%d",&n,&m);        siz=0;        for(int i=1;i<=n;i++){            scanf("%d",&arr[i]);            num[++siz]=arr[i];        }        for(int i=1;i<=m;i++){            scanf("%d%d%d",&L[i],&R[i],&H[i]);L[i]++;R[i]++;            num[++siz]=H[i];        }        init();        for(int i=1;i<=n;i++)            root[i]=update(root[i-1],Hash(arr[i]),1);        printf("Case %d:\n",++cas);        for(int i=1;i<=m;i++){            ans=0;            query(root[L[i]-1],root[R[i]],Hash(H[i]));            printf("%d\n",ans);        }    }    return 0;}

往右走进行了