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Submission #289399

# Submission time Handle Problem Language Result Execution time Memory
289399 2020-09-02T15:54:11 Z AMO5 Ljetopica (COI19_ljetopica) C++17
100 / 100
 234 ms 39744 KB 
//modified from koosaga's solution
#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define eb emplace_back
#define mt make_tuple
#define all(x) (x).begin(), (x).end()  
#define sz(x) int(x.size()) 
#define MOD 1000000007

typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;

const ll INF=63;
const int mxn=1e3+5;
bool DEBUG=0;

bitset<mxn>bs;
string s,t,a,b;
ll ans=0ll;
int n,k;
vll pw2;
bool vis[mxn][mxn][2][2];
pll dp[mxn][mxn][2][2]; //res, cnt of '1'

ll add(ll a, ll b){
	a%=MOD; b%=MOD;
	a+=b;
	if(a>=MOD)a-=MOD;
	if(a<0)a+=MOD;
	return a;
}

void init(int n){
	pw2.resize(n+1);
	pw2[0]=1ll;
	for(int i=1; i<=n; i++){
		pw2[i]=pw2[i-1]*2ll%MOD;
	}
	return;
}

pll f(int ptr, int left, bool match1, bool match2){
	if(left<0)return pll(0,0);
	if(ptr==n)return pll(0,left==0);
	if(vis[ptr][left][match1][match2])return dp[ptr][left][match1][match2];
	pll res(0,0);
	{
		bool nxtmatch = s[ptr]=='0';
		int kr = match1!=nxtmatch;
		pll r = f(ptr+1,left-kr,nxtmatch,bool(match2&(t[ptr]=='0')));
		res.fi = add(res.fi,r.fi);
		res.se = add(res.se,r.se);
	}
	if(match2==0||t[ptr]=='1'){
		bool nxtmatch = s[ptr]=='1';
		int kr = match1!=nxtmatch;
		pll r = f(ptr+1,left-kr,nxtmatch,match2);
		res.fi = add(res.fi,r.fi);
		res.fi = add(res.fi,r.se*pw2[n-1-ptr]);
		res.se = add(res.se,r.se);
	}
	//cerr<<ptr<<" "<<left<<" "<<match1<<" "<<match2<<": "<<res.fi<<" "<<res.se<<"\n";
	vis[ptr][left][match1][match2]=1;
	return dp[ptr][left][match1][match2]=res;
}

ll solve(string x){
	t=x;
	memset(vis,0,sizeof(vis));
	pll res1 = f(1,k,1,1);
	pll res2 = f(1,k,0,1);
	//cerr<<x<<" "<<res1.fi<<" "<<res1.se<<" "<<res2.fi<<" "<<res2.se<<"\n";
	res1.fi = add(res1.fi,res2.fi);
	res1.se = add(res1.se,res2.se);
	res1.fi = add(res1.fi, res1.se*pw2[n-1]);
	return res1.fi;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    //freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
    cin>>n>>k;
    cin>>s>>a>>b;
    s="R"+s;
    for(int i=0; i<n; i++)
		if(s[i]=='L')s[i]='0';
		else s[i]='1';
    init(n);
    a.back()--;
    for(int i=n-1; i>=0; i--){
		if(a[i]<'0'){
			a[i-1]--;
			a[i]='1';
		}else break;
	}
	//cerr<<a<<" "<<b<<"\n";
	ans = solve(b);
	//cerr<<ans<<"\n";
	if(a[0]=='1'){
		ans = add(ans,MOD-solve(a));
	}
	cout<<ans<<"\n";
	return 0;
}
	
// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 8576 KB Output is correct
2 Correct 5 ms 8320 KB Output is correct
3 Correct 6 ms 8064 KB Output is correct
4 Correct 5 ms 7936 KB Output is correct
5 Correct 6 ms 7808 KB Output is correct
6 Correct 5 ms 7424 KB Output is correct
7 Correct 6 ms 7296 KB Output is correct
8 Correct 5 ms 7144 KB Output is correct

Subtask #2
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4352 KB Output is correct
2 Correct 3 ms 4352 KB Output is correct
3 Correct 3 ms 4352 KB Output is correct
4 Correct 4 ms 4352 KB Output is correct
5 Correct 4 ms 4352 KB Output is correct
6 Correct 3 ms 4352 KB Output is correct
7 Correct 3 ms 4352 KB Output is correct
8 Correct 3 ms 4352 KB Output is correct
9 Correct 4 ms 4352 KB Output is correct
10 Correct 4 ms 4404 KB Output is correct
11 Correct 4 ms 4352 KB Output is correct
12 Correct 3 ms 4352 KB Output is correct
13 Correct 4 ms 4352 KB Output is correct
14 Correct 4 ms 4352 KB Output is correct
15 Correct 3 ms 4352 KB Output is correct

Subtask #3
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 99 ms 34168 KB Output is correct
2 Correct 80 ms 28448 KB Output is correct
3 Correct 92 ms 30532 KB Output is correct
4 Correct 190 ms 39672 KB Output is correct
5 Correct 82 ms 27512 KB Output is correct
6 Correct 217 ms 39744 KB Output is correct
7 Correct 58 ms 21088 KB Output is correct
8 Correct 85 ms 30200 KB Output is correct
9 Correct 9 ms 9728 KB Output is correct
10 Correct 79 ms 28664 KB Output is correct

Subtask #4
61.0 / 61.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 8576 KB Output is correct
2 Correct 5 ms 8320 KB Output is correct
3 Correct 6 ms 8064 KB Output is correct
4 Correct 5 ms 7936 KB Output is correct
5 Correct 6 ms 7808 KB Output is correct
6 Correct 5 ms 7424 KB Output is correct
7 Correct 6 ms 7296 KB Output is correct
8 Correct 5 ms 7144 KB Output is correct
9 Correct 3 ms 4352 KB Output is correct
10 Correct 3 ms 4352 KB Output is correct
11 Correct 3 ms 4352 KB Output is correct
12 Correct 4 ms 4352 KB Output is correct
13 Correct 4 ms 4352 KB Output is correct
14 Correct 3 ms 4352 KB Output is correct
15 Correct 3 ms 4352 KB Output is correct
16 Correct 3 ms 4352 KB Output is correct
17 Correct 4 ms 4352 KB Output is correct
18 Correct 4 ms 4404 KB Output is correct
19 Correct 4 ms 4352 KB Output is correct
20 Correct 3 ms 4352 KB Output is correct
21 Correct 4 ms 4352 KB Output is correct
22 Correct 4 ms 4352 KB Output is correct
23 Correct 3 ms 4352 KB Output is correct
24 Correct 99 ms 34168 KB Output is correct
25 Correct 80 ms 28448 KB Output is correct
26 Correct 92 ms 30532 KB Output is correct
27 Correct 190 ms 39672 KB Output is correct
28 Correct 82 ms 27512 KB Output is correct
29 Correct 217 ms 39744 KB Output is correct
30 Correct 58 ms 21088 KB Output is correct
31 Correct 85 ms 30200 KB Output is correct
32 Correct 9 ms 9728 KB Output is correct
33 Correct 79 ms 28664 KB Output is correct
34 Correct 215 ms 36716 KB Output is correct
35 Correct 99 ms 21240 KB Output is correct
36 Correct 137 ms 27644 KB Output is correct
37 Correct 221 ms 36708 KB Output is correct
38 Correct 65 ms 14868 KB Output is correct
39 Correct 171 ms 33872 KB Output is correct
40 Correct 54 ms 13756 KB Output is correct
41 Correct 165 ms 31888 KB Output is correct
42 Correct 213 ms 35868 KB Output is correct
43 Correct 190 ms 34680 KB Output is correct
44 Correct 196 ms 33800 KB Output is correct
45 Correct 124 ms 20216 KB Output is correct
46 Correct 180 ms 32376 KB Output is correct
47 Correct 186 ms 33392 KB Output is correct
48 Correct 133 ms 26300 KB Output is correct
49 Correct 13 ms 9600 KB Output is correct
50 Correct 206 ms 36600 KB Output is correct
51 Correct 129 ms 25340 KB Output is correct
52 Correct 148 ms 26644 KB Output is correct
53 Correct 234 ms 39416 KB Output is correct
54 Correct 105 ms 21768 KB Output is correct
55 Correct 225 ms 37548 KB Output is correct
56 Correct 226 ms 38776 KB Output is correct
57 Correct 50 ms 13568 KB Output is correct
58 Correct 230 ms 35836 KB Output is correct