Super Mario 【HDU - 4417】【可持久化线段树】

题目链接

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   处理不好就要T系列……因为去取upper_bound()的时候，可能会出现出现下角标为0的现象，这在线段树中是不允许的！

   然后就是处理的思路了，之前也做了区间第K大的数，这次来做区间K价值大的一下数的数目，不妨就对价值进行看作区间的处理，然后不断的去持久化，按照输入去更新即可。

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#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdlib>
#include <ctime>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f3f3f3f3f
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
#define MP(a, b) make_pair(a, b)
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 1e5 + 7;
int N, M, a[maxN], b[maxN], root[maxN], cnt, lson[maxN*20], rson[maxN*20], siz[maxN*20];
void buildTree(int &k, int l, int r)
{
    k = ++cnt;
    siz[k] = 0;
    if(l == r) return;
    int mid = HalF;
    buildTree(lson[k], l, mid);
    buildTree(rson[k], mid + 1, r);
}
void update(int old, int &now, int l, int r, int pos)
{
    now = ++cnt;
    siz[now] = siz[old];    lson[now] = lson[old];  rson[now] = rson[old];
    if(l == r)
    {
        siz[now]++;
        return;
    }
    int mid = HalF;
    if(pos <= mid) update(lson[old], lson[now], l, mid, pos);
    else update(rson[old], rson[now], mid + 1, r, pos);
    siz[now] = siz[lson[now]] + siz[rson[now]];
}
int query(int old, int now, int l, int r, int k)
{
    if(k >= r) return siz[now] - siz[old];
    int mid = HalF;
    if(k > mid) return siz[lson[now]] - siz[lson[old]] + query(rson[old], rson[now], mid + 1, r, k);
    else return query(lson[old], lson[now], l, mid, k);
}
int main()
{
    int T;  scanf("%d", &T);
    for(int Cas=1; Cas<=T; Cas++)
    {
        cnt = 0;
        scanf("%d%d", &N, &M);
        for(int i=1; i<=N; i++)
        {
            scanf("%d", &a[i]);
            b[i] = a[i];
        }
        sort(b + 1, b + N + 1);
        int diff = (int)(unique(b + 1, b + N + 1) - b - 1);
        buildTree(root[0], 1, diff);
        for(int i=1; i<=N; i++)
        {
            int pos = (int)(lower_bound(b + 1, b + diff + 1, a[i]) - b);
            update(root[i-1], root[i], 1, diff, pos);
        }
        printf("Case %d:\n", Cas);
        while(M--)
        {
            int l, r, k;    scanf("%d%d%d", &l, &r, &k);
            l++;    r++;
            int pos = (int)(upper_bound(b + 1, b + diff + 1, k) - b);
            if(pos > diff) printf("%d\n", r - l + 1);
            else if(pos <= 1) printf("0\n");
            else printf("%d\n", query(root[l-1], root[r], 1, diff, pos-1));
        }
    }
    return 0;
}