LeetCode | 28. Implement strStr()

28. Implement strStr()DescriptionImplement 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: 2Example 2:Input: haystack “aaaaa”, needle “bba”Output: -1Clarification:What should we return when needle is an empty string? This is a great question to ask during an interview.For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C’s strstr() and Java’s indexOf().Solution: (Java)classSolution{publicintstrStr(String haystack,String needle){if(needle.equals())return0;intneedleLenneedle.length();for(inti0;ihaystack.length();i){if(ineedleLenhaystack.length())break;if(haystack.charAt(i)needle.charAt(0)){intflag1;for(intj0;jneedleLen;j){if(haystack.charAt(ij)!needle.charAt(j)){flag0;break;}}if(flag1)returni;}}return-1;}}思路本题是求子串在字符串中第一次出现的位置遍历字符串时需要注意处理剩余长度小于给定子串的情况。