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| 1 | +/* Sample Input |
| 2 | +
|
| 3 | +3 |
| 4 | +Sample Output |
| 5 | +
|
| 6 | +6 |
| 7 | +
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| 8 | +
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| 9 | +Function Description |
| 10 | +Complete the factorial function in the editor below. Be sure to use recursion. |
| 11 | +
|
| 12 | +factorial has the following paramter: |
| 13 | +int n: an integer |
| 14 | +
|
| 15 | +Returns |
| 16 | +int: the factorial of n |
| 17 | +*/ |
| 18 | + |
| 19 | +#include <assert.h> |
| 20 | +#include <limits.h> |
| 21 | +#include <math.h> |
| 22 | +#include <stdbool.h> |
| 23 | +#include <stddef.h> |
| 24 | +#include <stdint.h> |
| 25 | +#include <stdio.h> |
| 26 | +#include <stdlib.h> |
| 27 | +#include <string.h> |
| 28 | + |
| 29 | +char* readline(); |
| 30 | + |
| 31 | +// Complete the factorial function below. |
| 32 | +int factorial(int n) { |
| 33 | +static int fact=1; |
| 34 | +while(n!=0) |
| 35 | +{ |
| 36 | + fact=fact*n; |
| 37 | + |
| 38 | + |
| 39 | +return factorial(n-1);} |
| 40 | +return fact; |
| 41 | +} |
| 42 | + |
| 43 | +int main() |
| 44 | +{ |
| 45 | + FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w"); |
| 46 | + |
| 47 | + char* n_endptr; |
| 48 | + char* n_str = readline(); |
| 49 | + int n = strtol(n_str, &n_endptr, 10); |
| 50 | + |
| 51 | + if (n_endptr == n_str || *n_endptr != '\0') { exit(EXIT_FAILURE); } |
| 52 | + |
| 53 | + int result = factorial(n); |
| 54 | + |
| 55 | + fprintf(fptr, "%d\n", result); |
| 56 | + |
| 57 | + fclose(fptr); |
| 58 | + |
| 59 | + return 0; |
| 60 | +} |
| 61 | + |
| 62 | +char* readline() { |
| 63 | + size_t alloc_length = 1024; |
| 64 | + size_t data_length = 0; |
| 65 | + char* data = malloc(alloc_length); |
| 66 | + |
| 67 | + while (true) { |
| 68 | + char* cursor = data + data_length; |
| 69 | + char* line = fgets(cursor, alloc_length - data_length, stdin); |
| 70 | + |
| 71 | + if (!line) { break; } |
| 72 | + |
| 73 | + data_length += strlen(cursor); |
| 74 | + |
| 75 | + if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') { break; } |
| 76 | + |
| 77 | + size_t new_length = alloc_length << 1; |
| 78 | + data = realloc(data, new_length); |
| 79 | + |
| 80 | + if (!data) { break; } |
| 81 | + |
| 82 | + alloc_length = new_length; |
| 83 | + } |
| 84 | + |
| 85 | + if (data[data_length - 1] == '\n') { |
| 86 | + data[data_length - 1] = '\0'; |
| 87 | + } |
| 88 | + |
| 89 | + data = realloc(data, data_length); |
| 90 | + |
| 91 | + return data; |
| 92 | +} |
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