Submission #907852

#	Time	Username	Problem	Language	Result	Execution time	Memory
907852		lighton	Ljetopica (COI19_ljetopica)	C++17	17 / 100	20 ms	16928 KiB

ljetopica

#include<bits/stdc++.h>
#define forf(i,a,b) for(int i = a; i<=b; i++)
#define forb(i,a,b) for(int i = a; i>=b; i--)
#define all(v) v.begin(),v.end()
typedef long long ll;
using namespace std;
ll mod = 1000000007;
ll binom[2001][2001];
ll dig[2001];
int N,K;
char ts[2001],tl[2001];
int A[2001];
int S[2001],L[2001];
void calc(){
    binom[0][0] = 1; binom[1][0] = 1; binom[1][1] = 1;
    forf(i,2,N){
        binom[i][0] = 1;
        forf(j,1,i){
            binom[i][j] = (binom[i-1][j-1]+binom[i-1][j]) % mod;
        }
    }
    dig[N-1] = 1;
    forb(i,N-2,0){
        dig[i] = dig[i+1] * 2 % mod;
    }
}


int main(){
    scanf("%d %d" , &N,&K);
    forf(i,1,N-1){
        char c; scanf("%c" , &c);
        if(c=='L') A[i] = 0;
        else A[i] = 1;
    }
    scanf("%s %s" , ts,tl);
    forf(i,0,N-1){
        if(ts[i] == '0') S[i] = 0;
        else S[i] = 1;
        if(tl[i] == '0') L[i] = 0;
        else L[i] = 1;
    }
    calc();


    ll ans = dig[0]*2*binom[N-1][K] % mod;
    forf(i,1,N-1){
        int l = i;
        int r = N-1-i;
        forf(j,0,K){
            ans += dig[i]*binom[l][j] %mod *binom[r][K-j] %mod;
            ans %= mod;
        }
    }
    printf("%lld" , ans);
}

Compilation message (stderr)

ljetopica.cpp: In function 'int main()':
ljetopica.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     scanf("%d %d" , &N,&K);
      |     ~~~~~^~~~~~~~~~~~~~~~~
ljetopica.cpp:32:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |         char c; scanf("%c" , &c);
      |                 ~~~~~^~~~~~~~~~~
ljetopica.cpp:36:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |     scanf("%s %s" , ts,tl);
      |     ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 14
• Subtask 3: 17 / 17
• Subtask 4: 0 / 61