Submission #828015

#	Time	Username	Problem	Language	Result	Execution time	Memory
828015		physics07	Radio Towers (IOI22_towers)	C++17	31 / 100	861 ms	31752 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], cut[100001], root[100001];
stack<int> stk;
vector<pair<int, int>> v;
vector<int> del, a;
struct maxseg {
    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;
struct minseg {
    int tree[100001*2], sz;
    void init(int n) {
        sz=n;
        memset(tree, 0x3f, sizeof(tree));
    }
    void update(int idx, int v) {
        for(tree[idx+=sz]=v; idx>1; idx>>=1) tree[idx>>1]=min(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=min(res, tree[l++]);
            if(~r&1) res=min(res, tree[r--]);
        }
        return res;
    }
} mtree;
struct PST {
    struct Node {
        int v, l, r;
    };
    vector<Node> tree;
    void mak() {tree.push_back({0, -1, -1});}
    void init(int node, int s, int e) {
        if(s==e) return;
        tree[node].l=(int)tree.size();
        mak();
        tree[node].r=(int)tree.size();
        mak();
        int m=s+e>>1;
        init(tree[node].l, s, m);
        init(tree[node].r, m+1, e);
    }
    void update(int node, int s, int e, int idx, int v, int prv) {
        if(s>idx || e<idx) return;
        tree[node]=tree[prv];
        tree[node].v+=v;
        if(s==e) return;
        int m=s+e>>1;
        if(idx<=m) {
            tree[node].l=(int)tree.size();
            mak();
            update(tree[node].l, s, m, idx, v, tree[prv].l);
        }
        else {
            tree[node].r=(int)tree.size();
            mak();
            update(tree[node].r, m+1, e, idx, v, tree[prv].r);
        }
    }
    int query(int node, int s, int e, int l, int r) {
        if(s>r || e<l) return 0;
        if(s>=l && e<=r) return tree[node].v;
        int m=s+e>>1;
        return query(tree[node].l, s, m, l, r)+query(tree[node].r, m+1, e, l, r);
    }
} pst;
void init(int N, vector<int> A) {
    n=N;
    for(auto i: A) a.push_back(i);
    tree.init(n);
    mtree.init(n);
    for(int i=0; i<n; i++) tree.update(i, a[i]);
    for(int i=0; i<n; i++) mtree.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) cut[i]=inf;
        else if(curr>a[i]) cut[i]=curr-a[i];
        else cut[i]=0;
        v.push_back({cut[i], i});
        del.push_back(cut[i]);
    }
    del.push_back(inf);
    sort(del.begin(), del.end());
    sort(v.begin(), v.end());
    root[n]=0;
    pst.mak();
    pst.init(0, 0, n-1);
    for(int i=n-1; i>=0; i--) {
        root[i]=(int)pst.tree.size();
        pst.mak();
        pst.update(root[i], 0, n-1, v[i].second, 1, root[i+1]);
    }
}

int max_towers(int l, int r, int d) {
    if(l==r || r==l+1) return 1;
    if(tree.query(l, r)-mtree.query(l, r)<d) return 1;
    int cnt=0;
    if(rt[l]==n || tree.query(l, rt[l]-1)>=d+a[l]) cnt++;
    if(lt[r]==-1 || tree.query(lt[r]+1, r)>=d+a[r]) cnt++;
    int idx=lower_bound(del.begin(), del.end(), d)-del.begin();
    return cnt+pst.query(root[idx], 0, n-1, l+1, r-1);
}

Compilation message (stderr)

towers.cpp: In member function 'void PST::init(int, int, int)':
towers.cpp:55:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   55 |         int m=s+e>>1;
      |               ~^~
towers.cpp: In member function 'void PST::update(int, int, int, int, int, int)':
towers.cpp:64:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   64 |         int m=s+e>>1;
      |               ~^~
towers.cpp: In member function 'int PST::query(int, int, int, int, int)':
towers.cpp:79:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   79 |         int m=s+e>>1;
      |               ~^~

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