Find the maximum depth or height of the tree

Implement a C program to find the maximum depth or height of the tree.

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct tree{
    int data;
    struct tree *left;
    struct tree *right;
};
struct queue{
    int front,rear;
    int size;
    struct tree* *array;
};

struct tree *newNode(int data){
    struct tree *t=(struct tree*)malloc(sizeof(struct tree));
    t->data = data;
    t->left = t->right = NULL;
    return t;
}
struct queue* createqueue(int size){
    struct queue *queue = (struct queue*)malloc(sizeof(struct queue));
    queue->size = size;
    queue->front = queue->rear = -1;
    queue->array = (struct tree**)malloc(size*sizeof(struct tree*));
    return queue;
}
void enqueue(struct tree *root,struct queue *queue){
    if(queue->rear == queue->size-1)
        return;
    queue->array[++queue->rear] = root;
    if(queue->front == -1)
        queue->front++;
}
struct tree *dequeue(struct queue *queue){
    if(queue->front==-1)
        return NULL;
    struct tree *t = queue->array[queue->front];
    if(queue->front==queue->rear)
    queue->front = queue->rear = -1;
    else
    queue->front++;
    return t;
}
void insert(struct tree **root,int data,struct queue* queue){
    struct tree *t = newNode(data);
    if(*root == NULL)
    *root = t;
    else{
        struct tree *front = queue->array[queue->front];
        if(front->left==NULL)
            front->left = t;
        else if(front->right==NULL)
            front->right = t;
        if(front->left!=NULL && front->right!=NULL)
            dequeue(queue);
    }
    enqueue(t,queue);
}
/*void inorder(struct tree *t){
    inorder(t->left);
    printf(" %d",t->data);
    inorder(t->right);
}
void preorder(struct tree *t){
    printf(" %d",t->data);
    preorder(t->left);
    preorder(t->right);
}
void postorder(struct tree *t){
    postorder(t->left);
    postorder(t->right);
    printf(" %d",t->data);
}
*/int max(int a,int b){
    if(a>b) return a;
    else return b;
}
int maxDepth(struct tree *root){
    if(root == NULL)
        return 0;
    else 
        return max(1+maxDepth(root->left),1+maxDepth(root->right));
}
int main()
{
struct tree* root=NULL;
char ans[3];
int data;
struct queue* queue = createqueue(50);
do{
    printf("Enter the element to be inserted in the tree\n");
        scanf("%d",&data);
        insert(&root,data,queue);
    printf("Do you want to insert another element?\n");
        scanf("%s",ans);
}while(strcmp(ans,"yes")==0);
/*printf("Inorder Traversal : The elements in the tree are");
    inorder(root);
    printf("\n");
    printf("Preorder Traversal : The elements in the tree are");
    preorder(root);
    printf("\n");
    printf("Postorder Traversal : The elements in the tree are");
    postorder(root);
*/    printf("Hight of tree is %d",maxDepth(root));
	return 0;
}