USACO 2017 February Contest, Silver Problem 1. Why Did the Cow Cross the Road

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USACO2017-FEB-S1

答案:

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;

typedef pair<int,int> pii;

multiset<int> chickens;
vector<pii> cows;
int C, N;

int main(void)
{
ifstream fin("helpcross.in");
ofstream fout("helpcross.out");

fin >> C >> N;
int x, y, total=0;
for (int i=0; i<C; i++) { fin >> x; chickens.insert(x); }
for (int i=0; i<N; i++) { fin >> x >> y; cows.push_back(pii(y,x)); }
sort (cows.begin(), cows.end());
for (int j=0; j<N; j++) {
auto which_chicken = chickens.lower_bound(cows[j].second);
if (which_chicken != chickens.end() && *which_chicken <= cows[j].first) {
total++;
chickens.erase(which_chicken);
}
}
fout << total << "\n";
return 0;
}