28. Implement strStr() Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 思路:子串匹配,朴素匹配.…

题目链接: https://leetcode.com/problems/implement-strstr/?tab=Description   Problem : 实现找子串的操作:如果没有找到则返回-1  ,如果找到则返回第一个匹配位置第一个字符的下标   遍历操作,依次遍历子串中的元素,从长串的第i个元素位置开始,当成功遍历结束子串所有元素时,返回此时的i即时所求结果, 如果此时的i+j已经等于长串的个数,那么表示没有找到,返回-1    参考代码: package leetcode_50;…

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",…

Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 问题:实现 strStr() 函数.即在  haystack 中匹配 needle 字符串. 可以理解为,实际上这道题是在问如何实现 KMP(Knuth–Morris–Pratt) 算法.这是个效率比较高的算法,只需要扫一遍 haystack 就可…

Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 解法: 这道题让我们在一个字符串中找另一个字符串第一次出现的位置,那我们首先要做一些判断,如果子字符串为空,则返回0,如果子字符串长度大于母字符串长度,则返回-1.然后我们开始遍历母字符串,我们并不需要遍历整个母字符串,而是遍历到剩下的长度和子字符…

Brute Force算法,时间复杂度 O(mn) def strStr(haystack, needle): m = len(haystack) n = len(needle) if n == 0: return 0 if m < n: return -1 for i in range(m - n - 1): for j in range(n): if haystack[i + j] != needle[j]: break elif j == n - 1: return i return -1…

题目描述: Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Update (2014-11-02): The signature of the function had been updated to return the index instead of the pointer. If you…

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",…

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",…

题目: class Solution { public: int strStr(string haystack, string needle) { if(needle.empty()){ return 0; } vector<int> next; int i = 0; int j = 0; int sLen = haystack.size(); int tLen = needle.size(); next = getNext(needle); while((i<sLen)&&am…