Submission #520176

#	Time	Username	Problem	Language	Result	Execution time	Memory
520176		qwerasdfzxcl	허수아비 (JOI14_scarecrows)	C++14	100 / 100	579 ms	13992 KiB

scarecrows

#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
const int INF = 1e9;
struct Seg{
    int tree[400400], sz;
    void init(int n){
        sz = n;
        fill(tree, tree+sz*2, INF);
    }
    void update(int p, int x){
        for (tree[p+=sz]=x;p>1;p>>=1) tree[p>>1] = min(tree[p], tree[p^1]);
    }
    int query(int l, int r){
        int ret = INF;
        for (l+=sz, r+=sz;l<r;l>>=1, r>>=1){
            if (l&1) ret = min(ret, tree[l++]);
            if (r&1) ret = min(ret, tree[--r]);
        }
        return ret;
    }
}tree1, tree2;

pair<int, int> a[200200];
ll ans;

void compress(vector<int> &a){
    sort(a.begin(), a.end());
    a.erase(unique(a.begin(), a.end()), a.end());
}

int getidx(int x, vector<int> &a){
    return lower_bound(a.begin(), a.end(), x) - a.begin();
}

void dnc(int l, int r){
    if (l==r) return;
    int m = (l+r)>>1;

    vector<pair<int, int>> V;
    for (int i=l;i<=r;i++) V.emplace_back(-a[i].second, i);
    sort(V.begin(), V.end());

    tree1.init(m-l+1);
    tree2.init(r-l+1);

    vector<int> st;
    int cnt = 0;

    for (auto &p:V){
        int i = p.second;
        if (i<=m){
            int L = -tree1.query(i-l, m-l+1);
            if (L==-INF) L = 0;
            int mn = tree2.query(L, cnt+1);
            ans += st.end() - lower_bound(st.begin(), st.end(), mn);

            tree1.update(i-l, -cnt);
        }
        else{
            tree2.update(cnt, i);
            while(!st.empty() && st.back() > i) st.pop_back();
            st.push_back(i);
        }
        cnt++;
    }

    dnc(l, m);
    dnc(m+1, r);
}

int main(){
    int n;
    scanf("%d", &n);
    vector<int> X, Y;
    X.push_back(-INF);
    Y.push_back(-INF);

    for (int i=1;i<=n;i++){
        scanf("%d %d", &a[i].first, &a[i].second);
        X.push_back(a[i].first);
        Y.push_back(a[i].second);
    }

    compress(X); compress(Y);
    assert((int)X.size()==n+1);
    assert((int)Y.size()==n+1);

    for (int i=1;i<=n;i++){
        a[i].first = getidx(a[i].first, X);
        a[i].second = getidx(a[i].second, Y);
    }

    sort(a+1, a+n+1);

    dnc(1, n);
    printf("%lld\n", ans);
    return 0;
}

Compilation message (stderr)

scarecrows.cpp: In function 'int main()':
scarecrows.cpp:75:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
scarecrows.cpp:81:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |         scanf("%d %d", &a[i].first, &a[i].second);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 85 / 85