dsa · easy

Index of First Occurrence

Return the starting index of the first place needle appears as a contiguous slice of haystack. If it never appears, return -1.

Arguments

• haystack — the text to search
• needle — the slice to find

Example

haystack = "sadbutsad", needle = "sad" → 0 (it also appears later at 6; take the first).

haystack = "practice", needle = "drill" → -1.

Constraints

1 <= haystack.length, needle.length <= 4*10^4 Hidden tests include near-max size for this bound; a slower-than-intended solution TLEs.

Examples

Example 1

Input:
"sadbutsad"
"sad"

Expected:
0

Example 2

Input:
"practice"
"drill"

Expected:
-1

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