Submission #2495505

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Source Code Expand

#include <fstream>
#include <cmath>
#include <vector>
#include <string>
#include <algorithm>
#include <cstring>
#include <map>
#include <queue>
#include <bitset>
#include <cassert>
#include <ctime>
#include <cstdlib>
#include <set>
#include <complex>

using namespace std;

const int SIZE = 1 << 10;

int pointer = SIZE;
char buffer[SIZE];

char Advance() {
    if (pointer == SIZE) {
        fread(buffer, 1, SIZE, stdin);
        pointer = 0;
    }
    return buffer[pointer++];
}

int Read() {
    int answer = 0;
    char ch = Advance();
    while (!isdigit(ch))
        ch = Advance();
    while (isdigit(ch)) {
        answer = answer * 10 + ch - '0';
        ch = Advance();
    }
    return answer;
}

const int MAXN = 5000;
const int MAXK = 5;
const int SIGMA = 26;

int k, n;
char s[1 + MAXN], t[1 + MAXK + 1];

bool Find(int m) {
    if (m > n)
        return false;
    for (int i = 1; i + m - 1 <= n; i++) {
        bool ok = true;
        for (int j = i; j <= i + m - 1; j++)
            if (s[j] != t[j - i + 1])
                ok = false;
        if (ok)
            return true;
    }
    return false;
}

void Backtracking(int m) {
    for (char ch = 'a'; ch <= 'z'; ch++) {
        m++;
        t[m] = ch;
        if (Find(m)) {
            k--;
            if (!k) {
                t[m + 1] = NULL;
                printf("%s\n", t + 1);
                exit(0);
            }
            Backtracking(m);
        }
        m--;
    }
}

int main() {
    //freopen("tema.in", "r", stdin);
    //freopen("tema.out", "w", stdout);
    scanf("%s%d", s + 1, &k);
    n = strlen(s + 1);
    Backtracking(0);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘void Backtracking(int)’:
./Main.cpp:71:26: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null]
                 t[m + 1] = NULL;
                          ^
./Main.cpp: In function ‘char Advance()’:
./Main.cpp:25:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
         fread(buffer, 1, SIZE, stdin);
                                      ^
./Main.cpp: In function ‘int main()’:
./Main.cpp:84:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s%d", s + 1, &k);
                             ^

Judge Result