답안 #234538

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
234538	2020-05-24T12:36:30 Z	shayan_p	Ljetopica (COI19_ljetopica)	C++14	100 / 100	37 ms	8440 KB

ljetopica

// Never let them see you bleed...

#include<bits/stdc++.h>

#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)

using namespace std;

typedef long long ll;
typedef pair<int,int> pii;

const int maxn = 1010 , mod = 1e9 + 7, inf = 1e9 + 10;

int fac[maxn], ifac[maxn];

int Pow(int a, int b){
    int ans = 1;
    for(; b; b>>=1, a = 1ll * a * a % mod)
	if(b & 1)
	    ans = 1ll * ans * a % mod;
    return ans;
}
int C(int n, int k){
    if(n < 0 || k < 0 || n < k)
	return 0;
    return 1ll * fac[n] * ifac[k] %mod * ifac[n-k] % mod;
}

int S[maxn], L[maxn], R[maxn], n, k, ans;
int dp[maxn][maxn][2], tw[maxn], NW;

void go(int pos, bool ch, int used, bool needL, bool needR){
    if(used > k)
	return;
    if(pos == n-1){
	if(used == k)
	    ans = (ans + NW) % mod;
	return;
    }
    if(!needL && !needR){
	ans = (1ll * ans + 1ll * C(n-1-pos, k-used) * NW) % mod;
	ans = (1ll * ans + dp[pos][k-used][ch]) % mod;
	return;
    }
    for(int x : {0, 1}){
	if(needL && x < L[pos])
	    continue;
	if(needR && R[pos] < x)
	    continue;
	bool ch2 = S[pos] != x;
	NW = (NW + tw[n-2-pos] * x) % mod;
	go(pos+1, ch2, used + (ch != ch2), needL && x == L[pos], needR && x == R[pos]);
	NW = (NW - tw[n-2-pos] * x) % mod;
    }
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie();

    fac[0] = 1;
    for(int i = 1; i < maxn; i++)
	fac[i] = 1ll * i * fac[i-1] % mod;
    ifac[maxn-1] = Pow(fac[maxn-1], mod-2);
    for(int i = maxn-2; i >= 0; i--)
	ifac[i] = 1ll * ifac[i+1] * (i+1) % mod;
    tw[0] = 1;
    for(int i = 1; i < maxn; i++)
	tw[i] = 2ll * tw[i-1] % mod;
    
    cin >> n >> k;
    string s, l, r;
    cin >> s >> l >> r;
    for(int i = 0; i < n-1; i++)
	S[i] = s[i] == 'R', L[i] = l[i+1] == '1', R[i] = r[i+1] == '1';
    for(int i = n-2; i >= 0; i--){
	for(int j = 0; j <= k; j++){
	    for(int w : {0, 1}){
		dp[i][j][w] = 1ll * (1ll * C(n-2-i, j) * (S[i] ^ w) + 1ll * C(n-2-i, j-1) * (S[i] ^ w ^ 1)) * tw[n-2-i] % mod;
		dp[i][j][w] = ( 1ll * dp[i][j][w] + 1ll * dp[i+1][j][w] + 1ll * (j == 0 ? 0 : dp[i+1][j-1][w ^ 1]) ) % mod;
	    }
	}
    }
    NW = tw[n-1], go(0, 0, 0, 1, 1);
    NW = tw[n-1], go(0, 1, 0, 1, 1);
    if(ans < 0)
	ans+= mod;
    return cout << ans << endl, 0;
}

Subtask #1
8.0 / 8.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	4480 KB	Output is correct
2	Correct	6 ms	4352 KB	Output is correct
3	Correct	6 ms	4096 KB	Output is correct
4	Correct	6 ms	3712 KB	Output is correct
5	Correct	6 ms	3712 KB	Output is correct
6	Correct	6 ms	3456 KB	Output is correct
7	Correct	6 ms	3200 KB	Output is correct
8	Correct	6 ms	3072 KB	Output is correct

Subtask #2
14.0 / 14.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	512 KB	Output is correct
2	Correct	5 ms	384 KB	Output is correct
3	Correct	5 ms	512 KB	Output is correct
4	Correct	5 ms	512 KB	Output is correct
5	Correct	5 ms	384 KB	Output is correct
6	Correct	5 ms	512 KB	Output is correct
7	Correct	5 ms	512 KB	Output is correct
8	Correct	5 ms	512 KB	Output is correct
9	Correct	4 ms	384 KB	Output is correct
10	Correct	5 ms	384 KB	Output is correct
11	Correct	5 ms	384 KB	Output is correct
12	Correct	5 ms	512 KB	Output is correct
13	Correct	5 ms	512 KB	Output is correct
14	Correct	5 ms	512 KB	Output is correct
15	Correct	5 ms	512 KB	Output is correct

Subtask #3
17.0 / 17.0

#	결과	실행 시간	메모리	Grader output
1	Correct	27 ms	8320 KB	Output is correct
2	Correct	22 ms	7552 KB	Output is correct
3	Correct	25 ms	7936 KB	Output is correct
4	Correct	37 ms	8440 KB	Output is correct
5	Correct	22 ms	7424 KB	Output is correct
6	Correct	37 ms	8312 KB	Output is correct
7	Correct	16 ms	6272 KB	Output is correct
8	Correct	23 ms	7928 KB	Output is correct
9	Correct	7 ms	4608 KB	Output is correct
10	Correct	22 ms	7552 KB	Output is correct

Subtask #4
61.0 / 61.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	4480 KB	Output is correct
2	Correct	6 ms	4352 KB	Output is correct
3	Correct	6 ms	4096 KB	Output is correct
4	Correct	6 ms	3712 KB	Output is correct
5	Correct	6 ms	3712 KB	Output is correct
6	Correct	6 ms	3456 KB	Output is correct
7	Correct	6 ms	3200 KB	Output is correct
8	Correct	6 ms	3072 KB	Output is correct
9	Correct	5 ms	512 KB	Output is correct
10	Correct	5 ms	384 KB	Output is correct
11	Correct	5 ms	512 KB	Output is correct
12	Correct	5 ms	512 KB	Output is correct
13	Correct	5 ms	384 KB	Output is correct
14	Correct	5 ms	512 KB	Output is correct
15	Correct	5 ms	512 KB	Output is correct
16	Correct	5 ms	512 KB	Output is correct
17	Correct	4 ms	384 KB	Output is correct
18	Correct	5 ms	384 KB	Output is correct
19	Correct	5 ms	384 KB	Output is correct
20	Correct	5 ms	512 KB	Output is correct
21	Correct	5 ms	512 KB	Output is correct
22	Correct	5 ms	512 KB	Output is correct
23	Correct	5 ms	512 KB	Output is correct
24	Correct	27 ms	8320 KB	Output is correct
25	Correct	22 ms	7552 KB	Output is correct
26	Correct	25 ms	7936 KB	Output is correct
27	Correct	37 ms	8440 KB	Output is correct
28	Correct	22 ms	7424 KB	Output is correct
29	Correct	37 ms	8312 KB	Output is correct
30	Correct	16 ms	6272 KB	Output is correct
31	Correct	23 ms	7928 KB	Output is correct
32	Correct	7 ms	4608 KB	Output is correct
33	Correct	22 ms	7552 KB	Output is correct
34	Correct	36 ms	8184 KB	Output is correct
35	Correct	17 ms	6016 KB	Output is correct
36	Correct	22 ms	7424 KB	Output is correct
37	Correct	32 ms	7936 KB	Output is correct
38	Correct	12 ms	4992 KB	Output is correct
39	Correct	30 ms	7680 KB	Output is correct
40	Correct	10 ms	4864 KB	Output is correct
41	Correct	26 ms	8064 KB	Output is correct
42	Correct	30 ms	8312 KB	Output is correct
43	Correct	30 ms	8056 KB	Output is correct
44	Correct	30 ms	7680 KB	Output is correct
45	Correct	15 ms	5888 KB	Output is correct
46	Correct	30 ms	7680 KB	Output is correct
47	Correct	30 ms	7808 KB	Output is correct
48	Correct	21 ms	7040 KB	Output is correct
49	Correct	7 ms	4352 KB	Output is correct
50	Correct	32 ms	8184 KB	Output is correct
51	Correct	20 ms	6912 KB	Output is correct
52	Correct	21 ms	7168 KB	Output is correct
53	Correct	34 ms	8316 KB	Output is correct
54	Correct	17 ms	6272 KB	Output is correct
55	Correct	30 ms	8312 KB	Output is correct
56	Correct	33 ms	8312 KB	Output is correct
57	Correct	10 ms	5120 KB	Output is correct
58	Correct	29 ms	8320 KB	Output is correct

답안 #234538

Compilation message

Subtask #1 8.0 / 8.0

Subtask #2 14.0 / 14.0

Subtask #3 17.0 / 17.0

Subtask #4 61.0 / 61.0

Subtask #1
8.0 / 8.0

Subtask #2
14.0 / 14.0

Subtask #3
17.0 / 17.0

Subtask #4
61.0 / 61.0