insertion sort

insertion sort c

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

typedef struct _node {
    int node_data;
    struct _node *next;
}node;

node *newNode(int data){
    node *ret = (node *)malloc(sizeof(node));
    ret->node_data = data;
    ret->next = NULL;
    return ret;
}

void insertion_sort_node(node **head, node *newn){
    node *current = *head;
    if (current == NULL){
        *head = newn;
        return;
    }
    
        if(current->node_data > newn->node_data){
            *head = newn;
            newn->next = current;
            return;
        }
    
    
    while(current->next != NULL){
        if(current->next->node_data > newn->node_data){
            newn->next = current->next;
            current->next = newn;
            return;
        }
        current = current->next;
    }
    current->next = newn;
    return;
}

node *delete_node(node **head, int cutn){
    node *current = *head;
    node *ret = NULL;
    if(current->node_data == cutn){
        ret = current;
        *head = current->next;
        return ret;
    }
    while(current->next != NULL){
        if(current->next->node_data == cutn){
            ret = current->next;
            current->next = ret->next;
            return ret;
        }
        current = current->next;
    }
    return ret;
}

void print_list(node *head){
    node *current = head;
    printf("list: ");
    while(current != NULL){
        printf(" %d ", current->node_data);
        current = current->next;
    }
    printf("\n");
}

int main (void){
    node *head = NULL;
    node *newn;
    int data;
    int flag;
    
    do{
        printf("put operationnumber\n");
        printf("0: quit/ 1: new node/ 2: delete data\n");
        scanf("%d", &flag);
        switch (flag){
            case 1: {
                printf("node data > ");
                scanf("%d", &data);
                newn = newNode(data);
                insertion_sort_node(&head, newn);
                print_list(head);
                break;
            }
            case 2: {
                printf("cut data > ");
                scanf("%d", &data);
                if(head == NULL){
                    printf("Error!\n");
                }else {
                newn = delete_node(&head, data);
                if(newn != NULL){
                    printf("\n%d deleted\n",data);
                }else{
                    printf("%d not found\n", data);    
                }
                print_list(head);
                free(newn);
                    }
                break;
            }
            default: break;
        }
    }while (flag != 0);
    
    printf("will be quit......\n ");
    
    if(head != NULL) free(head);
    return 0;
}