LeetCode OJ--Implement strStr()
http://oj.leetcode.com/problems/implement-strstr/
判断一个串是否为另一个串的子串
比较简单的方法,复杂度为O(m*n),另外还可以用KMP时间复杂度为O(m+n),之前面试的时候遇到过。
class Solution {
public:
bool isEqual(char *a,char *b)
{
char* chPointer = a;
char* chPointer2 = b;
while(*chPointer2!= '\0' && *chPointer!='\0' )
{
if(*chPointer == *chPointer2)
{
chPointer++;
chPointer2++;
}
else
return false;
}
return true;
}
char *strStr(char *haystack, char *needle) {
char* chPointer = haystack;
char* chPointer2 = needle;
if(haystack == NULL || needle ==NULL || haystack =="")
return NULL;
while(chPointer)
{
if(isEqual(chPointer,needle))
return chPointer;
chPointer++;
}
return NULL;
}
};
class Solution {
public:
void compute_prefix(const char* pattern,int next[])
{
int i;
int j = -;
const int m = strlen(pattern);
next[] = j;
for(i =;i<m;i++)
{
while(j>- && pattern[j+] != pattern[i]) j = next[j];
if(pattern[i]== pattern[j+])
j++;
next[i] = j;
}
}
int kmp(const char* text , const char* pattern)
{
int i;
int j = -;
const int n = strlen(text);
const int m = strlen(pattern);
if(n == m && m==)
return ;
if(m == )
return ;
int *next = (int *)malloc(sizeof(int) * m); compute_prefix(pattern, next); for(i = ;i <n;i++)
{
while(j >- && pattern[j+] != text[i])
j = next[j];
if(text[i] == pattern[j+]) j++;
if(j==m-)
{
free(next);
return i-j;
}
}
}
char *strStr(char *haystack, char *needle) {
int position = kmp(haystack,needle);
if(position == -)
return NULL;
else
return (char*)haystack + position;
}
};
LeetCode OJ--Implement strStr()的更多相关文章
- Leetcode OJ : Implement strStr() [ Boyer–Moore string search algorithm ] python solution
class Solution { public: int strStr(char *haystack, char *needle) { , skip[]; char *str = haystack, ...
- [LeetCode] 28. Implement strStr() 实现strStr()函数
Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle ...
- [leetcode 27]Implement strStr()
1 题目: Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if ...
- Leetcode #28. Implement strStr()
Brute Force算法,时间复杂度 O(mn) def strStr(haystack, needle): m = len(haystack) n = len(needle) if n == 0: ...
- 【leetcode】Implement strStr() (easy)
Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle ...
- 【leetcode】Implement strStr()
Implement strStr() Implement strStr(). Returns the index of the first occurrence of needle in haysta ...
- Java for LeetCode 028 Implement strStr()
Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle ...
- Java [leetcode 28]Implement strStr()
题目描述: Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if ...
- [LeetCode] 28. Implement strStr() 解题思路
Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle ...
- 44. leetcode 28. Implement strStr()
28. Implement strStr() Implement strStr(). Returns the index of the first occurrence of needle in ha ...
随机推荐
- Encryption-基础:base64加解密
环境:vc2003 .h /********** This library is free software; you can redistribute it and/or modify it und ...
- Python基础篇 -- 字典
字典 dict. 以 {} 表示, 每一项用逗号隔开, 内部元素用 key: value的形式来保存数据 例子: dict.{"JJ":"林俊杰"," ...
- javaEE(16)_Servlet监听器
一.监听器原理 1.监听器就是一个实现特定接口的普通java程序,这个程序专门用于监听一个java对象的方法调用或属性改变,当被监听对象发生上述事件后,监听器某个方法将立即被执行. 2.监听器典型案例 ...
- 【模拟】bzoj1686: [Usaco2005 Open]Waves 波纹
打完模拟题来庆祝一波:):感觉最近陷入一种“口胡五分钟打题两小时”的巨坑之中…… Description Input 第1行:四个用空格隔开的整数Pj Bi,B2,R. P(1≤P≤5)表示石 ...
- PERL学习之模式匹配
一.简介 模式指在字符串中寻找的特定序列的字符,由反斜线包含:/def/即模式def.其用法如结合函数split将字符串用某模式分成多个单词:@array = split(/ /, $line); ...
- python面向对象(C3算法)(六)
1. 了解python2和python3类的区别 python2在2.3之前使用的是经典类, 2.3之后, 使用的是新式类 2. 经典类的MRO 树形结构的深度优先遍历 -> 树形结构遍历 cl ...
- cocos2d-x游戏开发(一)之环境搭建篇
前言 进入研究生生涯已经有一段时间,感觉却没做些什么,实验室虽有一个很大的国家项目,但考虑到它这么的单一,总想利用业余时间做些什么,拓宽一下自己的知识面. 偶然机会,了解到cocos这个东东,恰好,实 ...
- PAT Basic 1069
1069 微博转发抽奖 小明 PAT 考了满分,高兴之余决定发起微博转发抽奖活动,从转发的网友中按顺序每隔 N 个人就发出一个红包.请你编写程序帮助他确定中奖名单. 输入格式: 输入第一行给出三个正整 ...
- iOS 唯一标示符 卸载后安装值不变
Vindor标示符 (IDFV-identifierForVendor) 这种叫法也是在iOS 6中新增的,不过获取这个IDFV的新方法被添加在已有的UIDevice类中.跟advertisingId ...
- IOS UITest 初始化 ViewController
import XCTest @testable import UITestDemo class UITestDemoTests: XCTestCase { var homevc:HomeViewCon ...