Add unfinished solutions

solutions/beecrowd/2866/2866.c

@@ -0,0 +1,55 @@
+#include <ctype.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+struct Stack {
+    char character;
+    struct Stack *next;
+};
+
+typedef struct Stack stack;
+
+void push(stack **decrypted_string, char character) {
+    stack *new_item = (stack *)malloc(sizeof(stack));
+
+    new_item->character = character;
+    new_item->next = *decrypted_string;
+    *decrypted_string = new_item;
+}
+
+char pop(stack **decrypted_string) {
+    char character = (*decrypted_string)->character;
+    stack *temp = *decrypted_string;
+
+    *decrypted_string = (*decrypted_string)->next;
+    free(temp);
+    return character;
+}
+
+int main() {
+    int16_t c;
+    char character;
+    stack *decrypted_string = NULL;
+
+    scanf("%d", &c);  // reads the number
+    character = getchar();  // reads the newline
+
+    character = getchar();
+
+    while (character != EOF) {
+        if (character != '\n') {
+            if (!isupper(character)) {
+                push(&decrypted_string, character);
+            }
+        } else {
+            while (decrypted_string != NULL) {
+                putchar(pop(&decrypted_string));
+            }
+            putchar('\n');
+        }
+        character = getchar();
+    }
+
+    return 0;
+}

solutions/beecrowd/2866/2866.cpp

@@ -0,0 +1 @@
+int main() {}

solutions/beecrowd/2866/WRONG

@@ -0,0 +1 @@
+c