1#include <stdio.h>
2#include <string.h>
3#include <stdlib.h>
4
5typedef struct {
6    char **history;
7    int size; 
8    int current;
9    int capacity;
10} BrowserHistory;
11
12BrowserHistory* browserHistoryCreate(char *homepage) {
13    BrowserHistory *obj = (BrowserHistory *)malloc(sizeof(BrowserHistory));
14    obj->history = (char **)malloc(5000 * sizeof(char*));
15    obj->history[0] = strdup(homepage);
16    obj->capacity = 5000;
17    obj->size = 1;
18    obj->current = 0;
19    return obj;
20}
21
22void browserHistoryVisit(BrowserHistory* obj, char *url) {
23    while (obj->size > obj->current + 1) {
24        free(obj->history[--obj->size]);
25    }
26    obj->history[obj->size++] = strdup(url);
27    obj->current = obj->size - 1;
28}
29
30char *browserHistoryBack(BrowserHistory* obj, int steps) {
31    obj->current = (steps > obj->current) ? 0 : obj->current - steps;
32    return obj->history[obj->current];
33}
34
35char *browserHistoryForward(BrowserHistory* obj, int steps) {
36    obj->current = (steps + obj->current >= obj->size) ? obj->size - 1 : obj->current + steps;
37    return obj->history[obj->current];
38}
39
40void browserHistoryFree(BrowserHistory* obj) {
41    for (int i = 0; i < obj->size; i++) {
42        free(obj->history[i]);
43    }
44    free(obj->history);
45    free(obj);
46}