Submission #826817

#	Time	Username	Problem	Language	Result	Execution time	Memory
826817		physics07	Radio Towers (IOI22_towers)	C++17	17 / 100	840 ms	7252 KiB

towers

#include "towers.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int inf=1e9+7;
int n, lt[100001], rt[100001];
map<int, int> del, sum;
stack<int> stk;
struct seg {
    int tree[100001*2], sz;
    void init(int n) {sz=n;}
    void update(int idx, int v) {
        for(tree[idx+=sz]+=v; idx>1; idx>>=1) tree[idx>>1]=max(tree[idx], tree[idx^1]);
    }
    int query(int l, int r) {
        int res=0;
        for(l+=sz, r+=sz; l<=r; l>>=1, r>>=1) {
            if(l&1) res=max(res, tree[l++]);
            if(~r&1) res=max(res, tree[r--]);
        }
        return res;
    }
} tree;
void init(int N, vector<int> a) {
    n=N;
    tree.init(n);
    for(int i=0; i<n; i++) tree.update(i, a[i]);
    for(int i=0; i<n; i++) {
        while(!stk.empty() && a[stk.top()]>a[i]) stk.pop();
        lt[i]=(stk.empty() ? -1 : stk.top());
        stk.push(i);
    }
    while(!stk.empty()) stk.pop();
    for(int i=n-1; i>=0; i--) {
        while(!stk.empty() && a[stk.top()]>a[i]) stk.pop();
        rt[i]=(stk.empty() ? n : stk.top());
        stk.push(i);
    }
    for(int i=0; i<n; i++) {
        int curr=inf;
        if(lt[i]>=0) curr=min(curr, tree.query(lt[i]+1, i));
        if(rt[i]<n) curr=min(curr, tree.query(i, rt[i]-1));
        if(curr==inf) {
            del[inf]++;
            continue;
        }
        if(curr>a[i]) del[curr-a[i]]++;
    }
    int prv=0;
    for(auto it=del.rbegin(); it!=del.rend(); it++) {
        prv+=it->second;
        sum[it->first]=prv;
    }
}

int max_towers(int l, int r, int d) {
    return sum.lower_bound(d)->second;
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 11
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 17 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23