Submission #935810

#	Time	Username	Problem	Language	Result	Execution time	Memory
935810		8pete8	Chorus (JOI23_chorus)	C++17	61 / 100	6091 ms	801676 KiB

chorus

#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<cassert>
#include<limits.h>
#include<cmath>
#include<set>
#include<numeric> //gcd(a,b)
#include<algorithm>
#include<bitset> 
#include<stack>
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define pppiiii pair<pii,pii>
#define ppii pair<int,pii>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define pb push_back
//#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#pragma GCC optimize ("03,unroll-loops")
#define int long long
const int mod=1e9+7,mxn=5005,lg=30,inf=1e18,minf=-1e18,Mxn=2e6,root=700;
void setIO(string name){
	ios_base::sync_with_stdio(0); cin.tie(0);		
	freopen((name+".in").c_str(),"r",stdin);		
	freopen((name+".out").c_str(),"w",stdout);	
}	
int dp[mxn+10][mxn+10];
int cost[mxn+10][mxn+10];
int pref[mxn*2+10];
vector<int>A,B;
int n,k;
string a;
void getcost(int st){
	int curcost=0;
	for(int i=A[st];i<=n*2;i++){
		if(a[i]=='A')pref[i]++;
		pref[i]+=pref[i-1];
	}
	for(int i=st;i<=n;i++){
		cost[st][i]=cost[st][i-1]+pref[B[i]];
	}
	for(int i=A[st];i<=2*n;i++)pref[i]=0;
	/*
	when introduced new B
	*/
}
void dc(int l,int r,int optl,int optr,int k){
	if(r<l)return;
	int mid=l+(r-l)/2;
	pii ans={inf,n};
	for(int i=optl;i<=min(optr,mid-1);i++){
		ans=min(ans,make_pair(dp[i][k-1]+cost[i+1][mid],i));
	}
	dp[mid][k]=ans.f;
	dc(l,mid-1,optl,ans.s,k);
	dc(mid+1,r,ans.s,optr,k);
}
int32_t main(){
	fastio
	cin>>n>>k;
	cin>>a;
	reverse(all(a));
	a='G'+a;
	A.pb(69);
	B.pb(420);
	for(int i=1;i<=n*2;i++){
		if(a[i]=='A')A.pb(i);
		else B.pb(i);
	}
	for(int i=1;i<=n;i++)getcost(i);
	for(int i=0;i<=k;i++)for(int j=1;j<=n;j++)dp[j][i]=inf;
	dp[0][0]=0;
	for(int i=1;i<=k;i++){//choose k use pref j
		dc(1,n,0,n,i);/*
		for(int j=1;j<=n;j++){
			for(int g=0;g<j;g++){
				dp[j][i]=min(dp[j][i],dp[g][i-1]+cost[g+1][j]);
			}
		}*/
	}
	cout<<dp[n][k];

	//can op to (n^2logn)? dac dp?
	//too lazy to prove :((
	
}

Compilation message (stderr)

chorus.cpp: In function 'void getcost(long long int)':
chorus.cpp:47:6: warning: unused variable 'curcost' [-Wunused-variable]
   47 |  int curcost=0;
      |      ^~~~~~~
chorus.cpp: In function 'void setIO(std::string)':
chorus.cpp:37:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |  freopen((name+".in").c_str(),"r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
chorus.cpp:38:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |  freopen((name+".out").c_str(),"w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 21 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13