HDU

题意

区间【1， n】上，每个点都有一块处在某高度的石头。给 m 个询问，区间【l， r】上高度不大于 h 的石头有多少块。

思路

主席树模板题

链接

https://vjudge.net/contest/177348#problem/N

代码

#include<cstdio>#include<iostream>#include<cstring>#include<algorithm>using namespace std;const int maxn = 1e5 + 10;int t, n, m;int A[maxn];int node[maxn << 3];int rot[maxn], lson[maxn << 3], rson[maxn << 3], num[maxn << 3], tt;int dct[maxn<<1], len;int a[maxn], b[maxn], h[maxn];void ins(int l, int r, int pre, int& now, int x){    now = ++tt;    if(l == r){        num[now] = num[pre] + 1;        return;    }    lson[now] = lson[pre], rson[now] = rson[pre];    int mid = (l + r) >> 1;    if(x <= mid) ins(l, mid, lson[pre], lson[now], x);    else ins(mid+1, r, rson[pre], rson[now], x);    num[now] = num[lson[now]] + num[rson[now]];}int query(int l, int r, int a, int b, int x, int y){    if(x > y) return 0;    if(x <= l && r <= y) return num[b] - num[a];    int mid = (l + r) >> 1;    int res = 0;    if(x <= mid) res += query(l, mid, lson[a], lson[b], x, y);    if(y > mid) res += query(mid+1, r, rson[a], rson[b], x, y);    return res;}int main(){    //freopen("in.txt", "r", stdin);    scanf("%d", &t);    int cas = 0;    while(t--)    {        printf("Case %d:\n", ++cas);        tt = 0;        scanf("%d %d", &n, &m);        for(int i = 1; i <= n; i++)        {            scanf("%d", A + i);            dct[i] = A[i];        }        for(int i = 1; i <= m; i++)        {            scanf("%d %d %d", a+i, b+i, h+i);            dct[n+i] = h[i];            a[i]++, b[i]++;        }        sort(dct + 1, dct + 1 + n + m);        len = unique(dct + 1, dct + n + m + 1) - dct - 1;        for(int i = 1; i <= n; i++)        {            int d = lower_bound(dct + 1, dct + len + 1, A[i]) - dct;            ins(1, len, rot[i-1], rot[i], d);        }        for(int i = 1; i <= m; i++)        {            int d = lower_bound(dct + 1, dct + len + 1, h[i]) - dct;            printf("%d\n", query(1, len, rot[a[i]-1], rot[b[i]], 1, d));        }    }    return 0;}