#!/usr/bin/python
# yigid balaban <fyb@fybx.dev>
# neetcode                      2024
# easy / find the first occurence in a string

# TC: O(n), MC: O(1)
def solution(haystack: str, needle: str) -> int:
    ph, pn = 0, 0
    position = -1
    while ph < len(haystack):
        print(ph, haystack[ph], pn, needle[pn])
        if haystack[ph] == needle[pn]:
            if position == -1:
                position = ph
            pn += 1
            if pn == len(needle):
                break
        else:
            if pn != 0:
                ph = position
            position, pn = -1, 0
        ph += 1
    return position if pn == len(needle) else -1


print(solution('sadbutsad', 'sad') == 0)
print(solution('leetcode', 'lecola') == -1)
print(solution('leetcode', 'etc') == 2)
print(solution('a', 'a') == 0)
print(solution('bbbab', 'ab') == 3)
print(solution('bbbaaaab', 'ab') == 6)
print(solution('aa', 'aaa') == -1)
print(solution('a', 'aaa') == -1)
print(solution('mississippi', 'issip') == 4)