這題是要呈現 indexOf 的邏輯，如果不匹配則會返回 -1。
LeetCode 題目連結
https://leetcode.com/problems/implement-strstr/
題目
Implement strStr().
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: haystack = "hello", needle = "ll"
Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba"
Output: -1
Clarification:
What should we return when needle is an empty string? This is a great question to ask during an interview.
Implement strStr().
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: haystack = "hello", needle = "ll" Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba" Output: -1
Clarification:
What should we return when
needle is an empty string? This is a great question to ask during an interview.Accept 作法
這題表面上好像很好寫，但很容易遺漏一些 case ，要小心。
Runtime: 0 ms
Memory: 38.6 MB
Java
Runtime: 0 ms
Memory: 38.6 MB
class Solution {
public int strStr(String haystack, String needle) {
if(needle.length() == 0 && haystack.length() == 0)
return 0;
if(needle.length() == 0){
return 0;
}
if(needle.length() > haystack.length()){
return -1;
}
if(needle.equals(haystack)){
return 0;
}
int size = haystack.length() - needle.length();
for(int i = 0;i <= size;i++){
String result = haystack.substring(i,i+needle.length());
if(result.equals(needle)){
return i;
}
}
return -1;
}
}
更多 LeetCode 相關資源
複習程式面試書籍
除了 LeetCode 練習外，我也入手了這本，題庫來自真正的面試，並非摘自教科書。它們反映出頂尖公司真正會出的題目，你可以藉此做好充分準備。
需要的話可以看看，寫得很仔細。
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