#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct queueNode {
	char *string;
	struct queueNode *next;
};

struct queue {
	struct queueNode *head;
	struct queueNode *tail;
};

char* stringInput() {
	int i = 0;
	int key = 0;
	char *string = nullptr;
	if (!(string = (char*)malloc(sizeof(char)))) {
		printf(" Memory error.\n");
		return NULL;
	}
	while ((key = getchar()) != '\n') {
		if (!(string = (char*)realloc(string, sizeof(char) * (i + 1)))) {
			printf(" Memory error.\n");
			return NULL;
		}
		string[i++] = key;
	}
	string[i] = '\0';
	return string;
}

int numberInput() {
	int number = 0;
	char buffer = 0;
	printf(" ");
	while ((!(scanf_s(" %d%c", &number, &buffer, 1))) || (buffer != '\n') || (number <= 0)) {
		printf(" You've entered the wrong value. Please, enter again: ");
		rewind(stdin);
	}
	return number;
}


struct queueNode *createQueue(struct queue *queuePoints) {
	struct queueNode *node = nullptr;
	if (!(node = (struct queueNode*)malloc(sizeof(struct queueNode)))) {
		return nullptr;
	}
	node->string = stringInput();
	node->next = NULL;
	if (queuePoints->tail == NULL) {
		queuePoints->head = queuePoints->tail = node;
		return node;
	}
	queuePoints->tail->next = node;
	queuePoints->tail = node;
	return node;
}

bool isSymmetric(struct queueNode *string) {
	int i = 0;
	int j = 0;
	int counter = 0;
	for (i = 0, j = strlen(string->string) - 1; i < (strlen(string->string) / 2); i++, j--) {
		if (string->string[i] == string->string[j]) {
			counter++;
		}
	}
	if (counter == 0) {
		return false;
	}
	if (counter == strlen(string->string) / 2) {
		return true;
	} else {
		return false;
	}
}

bool showQueue(struct queue *queuePoints) {
	struct queueNode *temp = queuePoints->head;
	bool flag = false;
	while (temp) {
		if (isSymmetric(temp)) {
			if (!flag) {
				printf(" These strings are symmetric:\n\n");
				flag = true;
			}
			printf(" %s\n\n", temp->string);
		}
			temp = temp->next;
	}
	if (!flag)
		return false;
	return true;
}

int main() {
	int switchOption = 0;
	char buffer = 0;
	int size = 0;
	struct queue *queuePoints = nullptr;
	if (!(queuePoints = (struct queue*)malloc(sizeof(struct queue)))) {
		return 0;
	}
	queuePoints->head = queuePoints->tail = NULL;
	printf(" Nice to meet you. Please, choose the required option:\n\n");
	do {
		printf(" 1. Queue elements input. \n 2. Queue elements output. \n 3. Exit. \n ");
		while (!(scanf_s("%d%c", &switchOption, &buffer, 1)) || switchOption < 1 || switchOption > 3 || buffer != '\n') {
			printf(" You've entered the wrong value. Please, enter again:\t");
			rewind(stdin);
		}
		system("CLS");
		switch (switchOption) {
		case 1:
			system("CLS");
			createQueue(queuePoints);
			break;
		case 2:
			system("CLS");
			if (!queuePoints->head) {
				printf(" Queue is empty.\n\n");
				break;
			}
			if (!showQueue(queuePoints)) {
				printf(" None are symmetric.\n\n");
			}
			break;
		case 3:
			system("CLS");
			free(queuePoints);
			printf("Thank you for using this programm!\nHave a good day!\n\n");
			system("exit");
		}
	} while (switchOption != 3);
	return 0;
}