Add extraLongFactorials implementation in C

Implemented a function to calculate and print extremely large factorials using an array-based approach. Includes necessary utility functions for input handling and trimming. This addition supports calculating factorials for very large numbers without overflow.

ExtraLongFactorials.c

@@ -0,0 +1,162 @@
+#include <assert.h>
+#include <ctype.h>
+#include <limits.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char* readline();
+char* ltrim(char*);
+char* rtrim(char*);
+
+int parse_int(char*);
+
+/*
+ * Complete the 'extraLongFactorials' function below.
+ *
+ * The function accepts INTEGER n as parameter.
+ */
+
+void extraLongFactorials(int n) {
+    // Array to store large numbers as digits
+    int result[1000];
+    result[0] = 1; // Initialize with 1
+    int result_size = 1;
+
+    // Multiply numbers from 2 to n
+    for (int x = 2; x <= n; x++) {
+        int carry = 0;
+
+        // Multiply x with the current result
+        for (int i = 0; i < result_size; i++) {
+            int prod = result[i] * x + carry;
+            result[i] = prod % 10; // Store last digit in the array
+            carry = prod / 10;    // Get the carry
+        }
+
+        // Store remaining carry in result array
+        while (carry) {
+            result[result_size] = carry % 10;
+            carry /= 10;
+            result_size++;
+        }
+    }
+
+    // Print the result in reverse (since the most significant digit is at the end)
+    for (int i = result_size - 1; i >= 0; i--) {
+        printf("%d", result[i]);
+    }
+    printf("\n");
+}
+
+int main()
+{
+    int n = parse_int(ltrim(rtrim(readline())));
+
+    extraLongFactorials(n);
+
+    return 0;
+}
+
+char* readline() {
+    size_t alloc_length = 1024;
+    size_t data_length = 0;
+
+    char* data = malloc(alloc_length);
+
+    while (true) {
+        char* cursor = data + data_length;
+        char* line = fgets(cursor, alloc_length - data_length, stdin);
+
+        if (!line) {
+            break;
+        }
+
+        data_length += strlen(cursor);
+
+        if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') {
+            break;
+        }
+
+        alloc_length <<= 1;
+
+        data = realloc(data, alloc_length);
+
+        if (!data) {
+            data = '\0';
+
+            break;
+        }
+    }
+
+    if (data[data_length - 1] == '\n') {
+        data[data_length - 1] = '\0';
+
+        data = realloc(data, data_length);
+
+        if (!data) {
+            data = '\0';
+        }
+    } else {
+        data = realloc(data, data_length + 1);
+
+        if (!data) {
+            data = '\0';
+        } else {
+            data[data_length] = '\0';
+        }
+    }
+
+    return data;
+}
+
+char* ltrim(char* str) {
+    if (!str) {
+        return '\0';
+    }
+
+    if (!*str) {
+        return str;
+    }
+
+    while (*str != '\0' && isspace(*str)) {
+        str++;
+    }
+
+    return str;
+}
+
+char* rtrim(char* str) {
+    if (!str) {
+        return '\0';
+    }
+
+    if (!*str) {
+        return str;
+    }
+
+    char* end = str + strlen(str) - 1;
+
+    while (end >= str && isspace(*end)) {
+        end--;
+    }
+
+    *(end + 1) = '\0';
+
+    return str;
+}
+
+int parse_int(char* str) {
+    char* endptr;
+    int value = strtol(str, &endptr, 10);
+
+    if (endptr == str || *endptr != '\0') {
+        exit(EXIT_FAILURE);
+    }
+
+    return value;
+}