jarvis.c

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


struct Point {
    int x;
    int y;
    struct Point *next;
};

static struct Point *head = NULL;
static struct Point *tail = NULL;

struct Point* createList(int x, int y) {
    struct Point *ptr = (struct Point*)malloc(sizeof(struct Point));
    if( NULL == ptr ) return NULL;

    ptr->x = x;
    ptr->y = y;
    ptr->next = NULL;
    head = tail = ptr;

    return ptr;
}

struct Point* extendList(int x, int y) {
    if( NULL == tail ) return createList(x, y);

    int i = 0;
    struct Point *tmp = head;
    struct Point *next = head->next;
    struct Point *ptr = (struct Point*)malloc(sizeof(struct Point));
    if( NULL == ptr ) return NULL;

    ptr->x = x;
    ptr->y = y;

    while ( NULL != tmp && x > tmp->x ) {
        i++;
        //printf("%02d,%02d\n", x, y, next->x, next->y);
        if( NULL == next ) {
            ptr->next = NULL;
            tmp->next = ptr;
            break;
        } else {
            if( x < next->x || (x == next->x && y < next->y) ) {
                ptr->next = next;
                tmp->next = ptr;
                break;
            }
        }

        tmp = tmp->next;
        next = tmp->next;
    }

    if( head == tmp ) {
        ptr->next = head;
        head = ptr;
    }

    printf("Durchläufe: %d\n", i);
    return ptr;
}

void printList() {
    struct Point *tmp = head;
    int i = 0;

    while ( NULL != tmp ) {
        printf("%04d: % 2d,% 2d\n", ++i, tmp->x, tmp->y);
        tmp = tmp->next;
        if(i>50) {
            printf("Whoops…\n");
            break;
        }
    }
}

void readNumbers() {
    int x, y, ch;
    bool lbState = false;  /* double linebreak? */

    while(1) {
        ch = getc(stdin);

        if(ch == EOF || ch == '\n') {
            if(lbState) break;

            extendList(x, y);
            lbState = true;
            continue;
        }
        lbState = false;

        ungetc(ch, stdin);
        if(scanf("%d %d", &x, &y) == EOF) break;
    }

    printList();
}


int main() {
    readNumbers();
    return 0;
}