【题目】
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome.
Note:
Have you consider that the string might be empty? This is a good question to ask during an interview.
For the purpose of this problem, we define empty string as valid palindrome.
【代码】
【方法1】
/*********************************
* 日期：2013-12-09
* 作者：SJF0115
* 题目: 125.Valid Palindrome
* 来源：http://oj.leetcode.com/problems/valid-palindrome/
* 结果：AC
* 来源：LeetCode
* 总结：
**********************************/
class Solution {
public:
bool isStr(char &ch){
//数字
if(ch >= '0' && ch <= '9'){
return true;
}
//小写字母
else if(ch >= 'a' && ch <= 'z'){
return true;
}
//大写字母
else if(ch >= 'A' && ch <= 'Z'){
//转换为小写
ch += 32;
return true;
}
return false;
}
bool isPalindrome(string s){
int i,j;
int len = s.length();
if(len == 0){
return true;
}
string str = "";
//去掉非数字字母字符
for(i = 0; i < len; i++){
if(isStr(s[i])){
str += s[i];
}
}
len = str.length();
for(i = 0,j = len - 1; i < j; i++,j--){
if(str[i] != str[j]){
return false;
}
}
return true;
}
};
【方法2】
class Solution {
public:
bool isStr(char &ch){
//数字
if(ch >= '0' && ch <= '9'){
return true;
}
//小写字母
else if(ch >= 'a' && ch <= 'z'){
return true;
}
//大写字母
else if(ch >= 'A' && ch <= 'Z'){
//转换为小写
ch += 32;
return true;
}
return false;
}
bool isPalindrome(string s){
int i,j;
int len = s.length();
if(len == 0){
return true;
}
len = s.length();
for(i = 0,j = len - 1; i < j;){
if(!isStr(s[i])){
i++;
continue;
}
if(!isStr(s[j])){
j--;
continue;
}
if(s[i] != s[j]){
return false;
}
i++;
j--;
}
return true;
}
};
【测试】
/*********************************
* 日期：2013-12-09
* 作者：SJF0115
* 题号: 题目: Valid Palindrome
* 来源：http://oj.leetcode.com/problems/valid-palindrome/
* 结果：AC
* 来源：LeetCode
* 总结：
**********************************/
#include <iostream>
#include <stdio.h>
using namespace std;
class Solution {
public:
bool isStr(char &ch){
//数字
if(ch >= '0' && ch <= '9'){
return true;
}
//小写字母
else if(ch >= 'a' && ch <= 'z'){
return true;
}
//大写字母
else if(ch >= 'A' && ch <= 'Z'){
//转换为小写
ch += 32;
return true;
}
return false;
}
bool isPalindrome(string s){
int i,j;
int len = s.length();
if(len == 0){
return true;
}
string str = "";
//去掉非数字字母字符
for(i = 0; i < len; i++){
if(isStr(s[i])){
str += s[i];
}
}
len = str.length();
for(i = 0,j = len - 1; i < j; i++,j--){
if(str[i] != str[j]){
return false;
}
}
return true;
}
};
int main() {
bool result;
string str = "A man, a plan, a canal: Panama";
//string str = "race a car";
Solution solution;
result = solution.isPalindrome(str);
if(result){
printf("This is a Palindrome\n");
}
else{
printf("sorry\n");
}
return 0;
}
