oj.uz

Submission #1101830

# Submission time Handle Problem Language Result Execution time Memory
1101830 2024-10-17T01:17:46 Z vjudge1 Necklace (Subtask 1-3) (BOI19_necklace1) C
85 / 85
 152 ms 636 KB 
#include <stdio.h>
#include <string.h>

#define MAX_N 3000

void build_lps_table(const char *S, int *lps, int N) {
    lps[0] = 0;
    for (int i = 1; i < N; i++) {
        int j = lps[i-1];
        while (j && S[j] != S[i])
            j = lps[j-1];
        if (S[j] == S[i]) j++;
        lps[i] = j;
    }
}

typedef struct {
    int max_len, i, j;
} res_t;

res_t max_len(const char *S, int N, const char *T, int M) {
    static char U[2 * MAX_N + 1];
    static char V[2 * MAX_N + 1];
    static int lps_u[2 * MAX_N + 1];
    static int lps_v[2 * MAX_N + 1];

    res_t res = {0};
    for (int i = 0; i <= N; i++) {
        // U = rev S[0,i) + # + rev T
        for (int k = 0; k < i; k++)
            U[k] = S[i-1-k];
        U[i] = '#';
        for (int k = 0; k < M; k++)
            U[k+i+1] = T[M-1-k];

        // V = S[i,N) + T
        memcpy(V, S + i, sizeof S[0] * (size_t)(N - i));
        V[N-i] = '#';
        memcpy(V + N - i + 1, T, sizeof T[0] * (size_t)M);

        build_lps_table(U, lps_u, i + 1 + M);
        build_lps_table(V, lps_v, N - i + M + 1);

        for (int j = 0; j <= M; j++) {
            int len = lps_u[M-1-j + i+1] + lps_v[j-1 + N-i+1];
            if (len > res.max_len) {
                res.max_len = len;
                res.i = i - lps_u[M-1-j + i+1];
                res.j = j - lps_v[j-1 + N-i+1];
            }
        }
    }
    return res;
}

void swap(char *a, char *b) {
    char tmp = *a;
    *a = *b;
    *b = tmp;
}

void reverse(char *S, int N) {
    int i = 0, j = N - 1;
    while (i < j)
        swap(S + i++, S + j--);
}

int main() {
    static char S[MAX_N + 1];
    static char T[MAX_N + 1];

    scanf("%s%s", S, T);
    int N = (int)strlen(S), M = (int)strlen(T);

    res_t res = max_len(S, N, T, M);
    reverse(T, M);
    res_t res2 = max_len(S, N, T, M);
    res2.j += res2.max_len - 1;
    res2.j = M - 1 - res2.j;

    if (res2.max_len > res.max_len)
        res = res2;

    printf("%d\n%d %d\n", res.max_len, res.i, res.j);

    return 0;
}

Compilation message

necklace.c: In function 'main':
necklace.c:72:5: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |     scanf("%s%s", S, T);
      |     ^~~~~~~~~~~~~~~~~~~

Subtask #1
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 3 ms 340 KB Output is correct
7 Correct 2 ms 636 KB Output is correct
8 Correct 3 ms 340 KB Output is correct
9 Correct 3 ms 448 KB Output is correct
10 Correct 2 ms 340 KB Output is correct
11 Correct 2 ms 340 KB Output is correct
12 Correct 2 ms 424 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 3 ms 340 KB Output is correct
7 Correct 2 ms 636 KB Output is correct
8 Correct 3 ms 340 KB Output is correct
9 Correct 3 ms 448 KB Output is correct
10 Correct 2 ms 340 KB Output is correct
11 Correct 2 ms 340 KB Output is correct
12 Correct 2 ms 424 KB Output is correct
13 Correct 131 ms 504 KB Output is correct
14 Correct 130 ms 484 KB Output is correct
15 Correct 152 ms 340 KB Output is correct
16 Correct 112 ms 484 KB Output is correct
17 Correct 84 ms 340 KB Output is correct
18 Correct 112 ms 476 KB Output is correct
19 Correct 94 ms 476 KB Output is correct
20 Correct 117 ms 484 KB Output is correct
21 Correct 121 ms 340 KB Output is correct