HDU6278 Just h-index

秒速五厘米 2022-01-07 05:17 171阅读 0赞

# 主席树+二分 #

每次对给定区间从1～区间长度len二分mid，查询区间内第mid大的数是不是大于等于mid。。

#include <bits/stdc++.h>
    #define INF 0x3f3f3f3f
    #define full(a, b) memset(a, b, sizeof a)
    using namespace std;
    typedef long long ll;
    inline int lowbit(int x){ return x & (-x); }
    inline int read(){
        int X = 0, w = 0; char ch = 0;
        while(!isdigit(ch)) { w |= ch == '-'; ch = getchar(); }
        while(isdigit(ch)) X = (X << 3) + (X << 1) + (ch ^ 48), ch = getchar();
        return w ? -X : X;
    }
    inline int gcd(int a, int b){ return a % b ? gcd(b, a % b) : b; }
    inline int lcm(int a, int b){ return a / gcd(a, b) * b; }
    template<typename T>
    inline T max(T x, T y, T z){ return max(max(x, y), z); }
    template<typename T>
    inline T min(T x, T y, T z){ return min(min(x, y), z); }
    template<typename A, typename B, typename C>
    inline A fpow(A x, B p, C lyd){
        A ans = 1;
        for(; p; p >>= 1, x = 1LL * x * x % lyd)if(p & 1)ans = 1LL * x * ans % lyd;
        return ans;
    }
    const int N = 200005;
    int n, q, tot, tree[20*N], lc[20*N], rc[20*N], a[N], b[N], root[N];
    
    int buildTree(int l, int r){
        int cur = ++tot;
        if(l == r) return tot;
        int mid = (l + r) >> 1;
        lc[cur] = buildTree(l, mid);
        rc[cur] = buildTree(mid + 1, r);
        return cur;
    }
    
    int modify(int rt, int l, int r, int p){
        int cur = ++tot;
        tree[cur] = tree[rt] + 1, lc[cur] = lc[rt], rc[cur] = rc[rt];
        if(l == r) return cur;
        int mid = (l + r) >> 1;
        if(p <= mid) lc[cur] = modify(lc[cur], l, mid, p);
        else rc[cur] = modify(rc[cur], mid + 1, r, p);
        return cur;
    }
    
    int query(int a, int b, int l, int r, int k){
        int p = tree[lc[a]] - tree[lc[b]];
        if(l == r) return l;
        int mid = (l + r) >> 1;
        if(k <= p) return query(lc[a], lc[b], l, mid, k);
        return query(rc[a], rc[b], mid + 1, r, k - p);
    }
    
    int main(){
    
        while(~scanf("%d%d", &n, &q)){
            full(a, 0), full(b, 0), full(tree, 0), full(lc, 0), full(rc, 0), full(root, 0);
            for(int i = 1; i <= n; i++) b[i] = a[i] = read();
            sort(b + 1, b + n + 1);
            int k = unique(b + 1, b + n + 1) - b - 1;
            root[0] = buildTree(1, k);
            for(int i = 1; i <= n; i++){
                int p = lower_bound(b + 1, b + k + 1, a[i]) - b;
                root[i] = modify(root[i - 1], 1, k, p);
            }
            while(q --){
                int u = read(), v = read();
                int l = 1, r = v - u + 1, len = v - u + 1;
                while(l < r){
                    int mid = (l + r + 1) >> 1;
                    int tmp = b[query(root[v], root[u - 1], 1, k, len - mid + 1)];
                    if(tmp < mid) r = mid - 1;
                    else l = mid;
                }
                printf("%d\n", l);
            }
        }
        return 0;
    }

转载于:https://www.cnblogs.com/onionQAQ/p/10727192.html