50181. Calculate the area

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

// typedef struct node{
//     struct node* rightPtr;
//     struct node* downPtr;
// }NODE;

int calArea(NODE* head){
    int ans = 0;
    NODE *d = head, *r = head;

    int ptr_d = 0, ptr_r = 0;
    while(r->rightPtr != NULL){
        r = r->rightPtr;
        ptr_r++;
    }

    while(ptr_r != ptr_d){
        ans += (ptr_r - ptr_d);
        d = d->downPtr, r = r->downPtr;

        while(d->rightPtr != NULL){
            d = d->rightPtr;
            ptr_d++;
        }
        while(r->rightPtr != NULL){
            r = r->rightPtr;
            ptr_r++;
        }
    }
    return ans;
}