std::string longestPalindrome(std::string s)
{
int n = s.length( );
if (n == 0)
{
return "";
}
std::string longest = s.substr(0, 1); // a single char itself is a palindrome
for (int center = 0; center < n - 1; center++) // 循环每个中心
{
// 以centerw为中心的最长回文串
std::string p1 = expandAroundCenter(s, center, center);
if (p1.length() > longest.length())
{
longest = p1;
}
// 以center和center + 1为中心的最长回文串
std::string p2 = expandAroundCenter(s, center, center + 1);
if (p2.length() > longest.length())
{
longest = p2;
}
}
return longest;
}
string longestPalindrome(string s) {
if(s.length()==0 || s.length()==1) return s;
string max, sub;
for(int i=0; i<s.length()-1; i++){
sub = expandAroundCenter(i, i, s);
if(sub.length() > max.length())
max = sub;
sub = expandAroundCenter(i, i+1, s);
if(sub.length() > max.length())
max = sub;
}
return max;
}
string longestPalindrome(string s) {
int n = s.length();
if (n == 0) return "";
string longest = s.substr(0, 1); // a single char itself is a palindrome
for (int i = 0; i < n-1; i++) {
string p1 = expandAroundCenter(s, i, i);
if (p1.length() > longest.length())
longest = p1;
string p2 = expandAroundCenter(s, i, i+1);
if (p2.length() > longest.length())
longest = p2;
}
return longest;
}
string longestPalindrome2(string s)
{
int n = s.size();
string result;
if (s.empty())
return "";
string longest = s.substr(0, 1);
for (int i = 0; i < n - 1; ++ i)
{
string s1 = expandAroundCenter(s, i, i);
if (s1.size() > longest.size())
longest = s1;
string s2 = expandAroundCenter(s, i, i + 1);
if (s2.size() > longest.size())
longest = s2;
}
return longest;
}
//第二种写法，从中心拓展
string longestPalindrome(string s){
int n=s.length();
if(n==0){
return "";
}
string longest=s.substr(0,1);
for(int i=0;i<n;i++){
string p1=expandAroundCenter( s,i,i);//围绕中心i使劲往两边走
if(p1.length()>=longest.length()){
longest=p1;
}
string p2=expandAroundCenter( s,i,i+1);//围绕中心i使劲往两边走
if(p2.length()>=longest.length()){
longest=p2;
}
}
return longest;
}
string longestPalindrome(string s) {
if (s.empty()) {
return "";
}
int n = s.size();
int maxlen = 1, start = 0, curlen = 0;
for(int i = 0; i < n-1; i++) {
curlen = expandAroundCenter(s, i, i);
if (curlen > maxlen) {
maxlen = curlen;
start = i - curlen/2;
}
curlen = expandAroundCenter(s, i, i+1);
if (curlen > maxlen) {
maxlen = curlen;
start = i - (curlen-2)/2;
}
}
string rtn (s, start, maxlen);
return rtn;
}
string LongestPalindromicSubstring::longestPalindrome(string s) {
int n = s.size();
if (n == 0)
return "";
string result = s.substr(0, 1);
for (int i = 0; i < n - 1; i++) {
string p1 = expandAroundCenter(s, i, i);
if (p1.size() > result.size())
result = p1;
string p2 = expandAroundCenter(s, i, i + 1);
if (p2.size() > result.size())
result = p2;
}
return result;
}
char * longestPalindrome(char * s) {
if (s == NULL)
return NULL;
int len = strlen(s);
int start_position = 0;
int max_len = 0;
int i = 0;
for (; i<len; ++i) {
int l0 = expandAroundCenter(s, len, i, i);
int l1 = expandAroundCenter(s, len, i, i+1);
l0 = l0>l1 ? l0 : l1;
if (l0 > max_len) {
max_len = l0;
start_position = i - (l0-1)/2;
}
}
char * result = (char *)malloc((max_len+1)*sizeof(char));
strncpy(result, &s[start_position], max_len);
result[max_len] = '\0';
return result;
}
string longestPalindrome(string s) {
if( s.size() == 0 )
return NULL;
int start = 0, end = 0;
for( int i = 0; i < s.size(); i++ )
{
int len1 = expandAroundCenter( s, i, i );
int len2 = expandAroundCenter( s, i, i + 1 );
int len = max( len1, len2 );
if( len > (end - start) )
{
start = i - (len - 1)/2;
end = i + len/2;
}
}
return s.substr(start, end - start + 1);
}
