Submission #129121

#	Time	Username	Problem	Language	Result	Execution time	Memory
129121		mahmoudbadawy	Lamps (JOI19_lamps)	C++17	0 / 100	154 ms	28460 KiB

lamp

#include <bits/stdc++.h>

using namespace std;

const int N=1e6+5;

int d1[N],d2[N];
int mem[N];
string a,b;
int n;

int stat(int x)
{
	// 0 01 1 10 2 00 3 11
	if(a[x]==b[x])
		return (a[x]=='0'?2:3);
	return (a[x]=='0'?0:1);
}

int f1(int x,int y)
{
	return d1[y]-(x?d1[x-1]:0)+(stat(x)<2);
}

int f2(int x,int y)
{
	return d2[y]-(x?d2[x-1]:0)+(stat(x)>=2);
}

vector<int> cmp;
int pos[N],st[N];

int main()
{
	cin >> n >> a >> b;
	cmp.push_back(stat(0));
	for(int i=1;i<n;i++)
	{
		if(stat(i)==cmp.back())
			pos[i]=pos[i-1];
		else
		{
			pos[i]=cmp.size();
			st[cmp.size()]=i;
			cmp.push_back(stat(i));
		}
	}
	for(int i=1;i<n;i++)
	{
		d1[i]=(stat(i)!=stat(i-1)&&(stat(i)<2))+d1[i-1];
		int mn=cmp[pos[i]],mx=cmp[pos[i]-1];
		d2[i]=((stat(i)!=stat(i-1))&&(stat(i)>=2))+d2[i-1];
		if(stat(i)!=stat(i-1))
		{
			if(pos[i]>=2&&cmp[pos[i]]==cmp[pos[i]-2] && a[i]!=a[i-1])
			{
				if(stat(i)<2)
					d1[i]--;
				if(stat(i)>=2)
					d2[i]--;
			}
		}
	}
	/*for(int i=0;i<n;i++)
		cout << d1[i] << " ";
	cout << endl;
	for(int i=0;i<n;i++)
		cout << d2[i] << " ";
	cout << endl;*/
	for(int i=n-1;i>=0;i--)
	{
		mem[i]=(1<<30);
		for(int j=i;j<n;j++)
		{
			mem[i]=min(mem[i],min(f1(i,j)+mem[j+1],1+f2(i,j)+mem[j+1]));
		}
		if(pos[i]+2<n)
		{
			int ind=st[pos[i]+2];
			if(stat(ind)!=stat(ind-1))
			{
				if(cmp[ind]==cmp[i] && a[ind]!=a[ind-1])
				{
					for(int j=ind;j<n;j++)
					{
						if(stat(ind)<2)
							d1[j]++;
						if(stat(ind)>=2)
							d2[j]++;
					}
				}
			}
		}
	}
	cout << mem[0] << endl;
}

Compilation message (stderr)

lamp.cpp: In function 'int main()':
lamp.cpp:51:7: warning: unused variable 'mn' [-Wunused-variable]
   int mn=cmp[pos[i]],mx=cmp[pos[i]-1];
       ^~
lamp.cpp:51:22: warning: unused variable 'mx' [-Wunused-variable]
   int mn=cmp[pos[i]],mx=cmp[pos[i]-1];
                      ^~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 4
• Subtask 4: 0 / 49