Submission #28211

#	Time	Username	Problem	Language	Result	Execution time	Memory
28211		top34051	Port Facility (JOI17_port_facility)	C++14	100 / 100	2013 ms	74152 KiB

port_facility

#include<bits/stdc++.h>
using namespace std;
#define maxn 1000005
#define mod 1000000007LL
int n;
int head[maxn*2];
bool check[maxn*2];
pair<int,int> p[maxn];
map<int,int> pos;
int findhead(int x) {
    if(x==head[x]) return x;
    return head[x] = findhead(head[x]);
}
void fus(int x,int y) {
    head[findhead(x)] = findhead(y);
}
main() {
    int i;
    long long ans;
    map<int,int>::iterator st,ft;
    scanf("%d",&n);
    for(i=0;i<n;i++) scanf("%d%d",&p[i].first,&p[i].second);
    sort(&p[0],&p[n]);
    for(i=0;i<n*2;i++) head[i] = i;
    for(i=0;i<n;i++) {
        st = pos.lower_bound(p[i].first);
        ft = pos.lower_bound(p[i].second);
        while(st!=ft) {
            fus(i,st->second+n); fus(i+n,st->second);
            if(findhead(st->second)==findhead((--ft)->second)) break;
            ++ft;
            st++;
        }
        pos[p[i].second] = i;
    }
    ans = 1;
    for(i=0;i<n;i++) {
        if(findhead(i)==findhead(i+n)) ans = 0;
        else check[findhead(i)] = check[findhead(i+n)] = 1;
    }
    for(i=0;i<n;i++) if(check[i]) ans = (ans*2)%mod;
    printf("%lld",ans);
}

Compilation message (stderr)

port_facility.cpp:17:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^
port_facility.cpp: In function 'int main()':
port_facility.cpp:21:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
                   ^
port_facility.cpp:22:60: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(i=0;i<n;i++) scanf("%d%d",&p[i].first,&p[i].second);
                                                            ^

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 56 / 56
• Subtask 4: 22 / 22