Submission #62810

#	Time	Username	Problem	Language	Result	Execution time	Memory
62810		kdh9949	허수아비 (JOI14_scarecrows)	C++17	100 / 100	243 ms	79880 KiB

scarecrows

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pii = pair<int, int>;
#define X first
#define Y second

const int N = 200005, inf = int(2e9);

int n, ac, bc;
pii a[N], b[N], as[N], bs[N];

ll f(int s, int e){
    if(s == e){
        b[s] = a[s];
        return 0;
    }
    int m = (s + e) / 2;
    ll r = f(s, m) + f(m + 1, e);
    int p, q, cc = s;
    as[0] = {inf, -inf}; bs[0] = {-inf, -inf + 1};
    ac = bc = 1;
    for(p = s, q = m + 1; p <= m || q <= e; ){
        if(q > e || (p <= m && b[p].Y < b[q].Y)){
            a[cc++] = b[p];
            while(as[ac - 1].X < b[p].X) ac--;
            as[ac++] = b[p++];
        }
        else{
            a[cc++] = b[q];
            while(bs[bc - 1].X > b[q].X) bc--;
            r += int(as + ac -
                    lower_bound(as, as + ac, bs[bc - 1], [](pii p, pii q){
                        return p.Y < q.Y;
                    }));
            bs[bc++] = b[q++];
        }
    }
    for(int i = s; i <= e; i++) b[i] = a[i];
    return r;
}

int main(){
    scanf("%d", &n);
    for(int i = 0; i < n; i++){
        scanf("%d%d", &a[i].X, &a[i].Y);
    }
    sort(a, a + n);
    printf("%lld\n", f(0, n - 1));
}

Compilation message (stderr)

scarecrows.cpp: In function 'int main()':
scarecrows.cpp:45:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
scarecrows.cpp:47:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &a[i].X, &a[i].Y);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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