Implement strStr
Problem Return the index of the first occurrence of needle in haystack, or -1 if absent (empty needle → 0).
Input / Output
- Input: strings haystack, needle.
- Output: first match index or -1.
Constraints
- Lengths up to 510^4; the naive O(nm) sliding compare is acceptable; know a linear-time option.
Example
- haystack = "sadbutsad", needle = "sad" → 0.
asked …