Submission #129821

#	Time	Username	Problem	Language	Result	Execution time	Memory
129821		pzdba	Ljetopica (COI19_ljetopica)	C++14	17 / 100	44 ms	31864 KiB

ljetopica

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
char s[1002], a[1002], b[1002];
ll dp[1002][1002][2], cnt[1002][1002][2];
int n, k;

int dfs(char *t){
    if(s[1] == '0') return 0;

    memset(dp, 0, sizeof(dp));
    memset(cnt, 0, sizeof(cnt));

    dp[1][0][0] = 1;
    cnt[1][0][0] = 1;

    dp[1][0][1] = 1;
    cnt[1][0][1] = 1;
    for(int i=2;i<=n;i++){
        for(int j=0;j<=k;j++){
            if(s[i] == 'L'){
                dp[i][j][0] = (dp[i][j][0] + dp[i-1][j][0]*2)%mod;
                cnt[i][j][0] = (cnt[i][j][0] + cnt[i-1][j][0])%mod;

                dp[i][j][1] = (dp[i][j][1] + dp[i-1][j][1]*2 + cnt[i-1][j][1])%mod;
                cnt[i][j][1] = (cnt[i][j][1] + cnt[i-1][j][1])%mod;

                if(j != k){
                    dp[i][j+1][1] = (dp[i][j+1][1] + dp[i-1][j][0]*2 + cnt[i-1][j][0])%mod;
                    cnt[i][j+1][1] = (cnt[i][j+1][1] + cnt[i-1][j][0])%mod;

                    dp[i][j+1][0] = (dp[i][j+1][0] + dp[i-1][j][1]*2)%mod;
                    cnt[i][j+1][0] = (cnt[i][j+1][0] + cnt[i-1][j][1])%mod;
                }
            }
            else{
                dp[i][j][0] = (dp[i][j][0] + dp[i-1][j][0]*2 + cnt[i-1][j][0])%mod;
                cnt[i][j][0] = (cnt[i][j][0] + cnt[i-1][j][0])%mod;

                dp[i][j][1] = (dp[i][j][1] + dp[i-1][j][1]*2)%mod;
                cnt[i][j][1] = (cnt[i][j][1] + cnt[i-1][j][1])%mod;

                if(j != k){
                    dp[i][j+1][1] = (dp[i][j+1][1] + dp[i-1][j][0]*2)%mod;
                    cnt[i][j+1][1] = (cnt[i][j+1][1] + cnt[i-1][j][0])%mod;

                    dp[i][j+1][0] = (dp[i][j+1][0] + dp[i-1][j][1]*2 + cnt[i-1][j][1])%mod;
                    cnt[i][j+1][0] = (cnt[i][j+1][0] + cnt[i-1][j][1])%mod;
                }
            }
        }
    }
    return (dp[n][k][0] + dp[n][k][1])%mod;
}

int main(){
    scanf("%d%d", &n, &k);
    scanf("%s", s+2);    
    scanf("%s", a+1);
    scanf("%s", b+1);

    for(int i=n;i>=1;i--){
        if(a[i] == '1'){
            a[i] = '0';
            for(int j=i+1;j<=n;j++) a[j] = '1';
            break;
        }
    }

    int res1 = dfs(a);
    // int res2 = dfs(b);
    int res2 = 0;

    printf("%d\n", (res1 - res2 + mod)%mod);
}

Compilation message (stderr)

ljetopica.cpp: In function 'int main()':
ljetopica.cpp:58:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~
ljetopica.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", s+2);    
     ~~~~~^~~~~~~~~~~
ljetopica.cpp:60:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", a+1);
     ~~~~~^~~~~~~~~~~
ljetopica.cpp:61:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", b+1);
     ~~~~~^~~~~~~~~~~

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