Znzryb's Blog
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ABC-382-C - Kaiten Sushi

Posted on Edited on

思路讲解

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struct cmp{
	bool operator()(const pll &a,const pll &b) const {
		return a.fi>b.fi;
	}
};
multiset<pll,cmp> B;

给multiset的cmp记得加const，否则有可能CE

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for(multiset<pll>::iterator it=B.begin();it!=B.end();){
	if(it->first<A[i]){
		break;
	}
	multiset<pll>::iterator next_it=next(it);
	ans[it->second]=i;
	B.erase(it);
	it=next_it;
}

然后erase（）只能传入iterator，不能够传入reverse_iterator

AC代码

https://atcoder.jp/contests/abc382/submissions/62419496

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// Problem: C - Kaiten Sushi
// Contest: AtCoder - AtCoder Beginner Contest 382
// URL: https://atcoder.jp/contests/abc382/tasks/abc382_c
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
// by znzryb
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = a; i <= b; ++i)
#define ROF(i, a, b) for (int i = a; i >= b; --i)
#define all(x) x.begin(),x.end()
#define CLR(i,a) memset(i,a,sizeof(i))
#define fi first
#define se second
#define pb push_back

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr;
typedef double DB;
const ll MAXN=static_cast<ll>(2e5)+10,INF=static_cast<ll>(5e18)+3;

ll N,M,A[MAXN];
// pll B[MAXN];
struct cmp{
	bool operator()(const pll &a,const pll &b) const {
		return a.fi>b.fi;
	}
};
multiset<pll,cmp> B;
ll ans[MAXN];

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin>>N>>M;
	FOR(i, 1, N){
		cin>>A[i];
	}
	FOR(i, 1, M){
		ll b;
		cin>>b;
		B.insert({b,i});
	}
	FOR(i,1,M){
		ans[i]=-1;
	}
	
	FOR(i,1,N){
		for(multiset<pll>::iterator it=B.begin();it!=B.end();){
			if(it->first<A[i]){
				break;
			}
			multiset<pll>::iterator next_it=next(it);
			ans[it->second]=i;
			B.erase(it);
			it=next_it;
		}
	}
	FOR(i,1,M){
		cout<<ans[i]<<'\n';
	}
	return 0;
}
/*
AC
https://atcoder.jp/contests/abc382/submissions/62419496
*/

心路历程（WA，TLE，MLE……）