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description:
Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: haystack = "sadbutsad", needle = "sad"
Output: 0
Explanation: "sad" occurs at index 0 and 6.
The first occurrence is at index 0, so we return 0.
Example 2:
Input: haystack = "leetcode", needle = "leeto"
Output: -1
Explanation: "leeto" did not occur in "leetcode", so we return -1.
Constraints:
1 <= haystack.length, needle.length <= 104
haystack and needle consist of only lowercase English characters.
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solution:
class Solution {
public:
int strStr(string haystack, string needle) {
const int m = haystack.length();
const int n = needle.length();
for (int i = 0; i < m - n + 1; i++)
if (haystack.substr(i, n) == needle)
return i;
return -1;
}
};
leetcode
challenge
Here is the link for the problem:
https://leetcode.com/problems/find-the-index-of-the-first-occurrence-in-a-string/
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