-
-
Notifications
You must be signed in to change notification settings - Fork 299
/
5.cpp
175 lines (164 loc) · 5.12 KB
/
5.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
__________________________________________________________________________________________________
4ms
class Solution {
public:
string longestPalindrome(string s) {
if (s.empty()) return "";
if (s.size() == 1) return s;
int min_start = 0, max_len = 1;
for (int i = 0; i < s.size();) {
int j = i, k = i;
while (k < s.size()-1 && s[k+1] == s[k]) ++k; // Skip duplicate characters.
i = k+1;
while (k < s.size()-1 && j > 0 && s[k + 1] == s[j - 1]) { ++k; --j; } // Expand.
int new_len = k - j + 1;
if (new_len > max_len) { min_start = j; max_len = new_len; }
}
return s.substr(min_start, max_len);
}
};
__________________________________________________________________________________________________
4ms
class Solution {
public:
string longestPalindrome(string s) {
if (s.size() < 2) return s;
int n = s.size(), maxLen = 0, start = 0;
for (int i = 0; i < n;) {
if (n - i <= maxLen / 2) break;
int left = i, right = i;
while (right < n - 1 && s[right + 1] == s[right]) ++right;
i = right + 1;
while (right < n - 1 && left > 0 && s[right + 1] == s[left - 1]) {
++right; --left;
}
if (maxLen < right - left + 1) {
maxLen = right - left + 1;
start = left;
}
}
return s.substr(start, maxLen);
}
};
__________________________________________________________________________________________________
12ms
class Solution {
public:
tuple<int, int, int> find_max_pal(const string &s, int left, int right) {
if (left-1 >= 0 && right+1 < s.size() && s[left-1] == s[right+1])
return find_max_pal(s, left-1, right+1);
return make_tuple(right - left + 1, left, right);
}
string expand(string s) {
if (s.size() < 1) return "";
string result = "#";
for (int i=0; i<s.size(); i++) {
result += s[i];
result += "#";
}
return result;
}
string longestPalindrome(string s) {
s = expand(s);
cout << s << endl;
vector<int> pal(s.size(), 0);
int c=-1, r=-1;
for (int i=0; i<s.size(); i++) {
int mirror = c - (i - c);
int offset = 0;
if (i < r)
offset = min(r - i, pal[mirror]);
auto result = find_max_pal(s, i-offset, i+offset);
int left = get<1>(result), right = get<2>(result);
int len = (right - left) / 2;
pal[i] = len;
if (r < right) {
c = i;
r = right;
}
}
int len = 0, index = -1;
for (int i=0; i<pal.size(); i++) {
if (len < pal[i]) {
len = pal[i];
index = i;
}
}
stringstream ss;
int last = min(index + len, (int) s.size());
for (int i=index-len; i<=last; i++) {
if (s[i] == '#') continue;
ss << s[i];
}
return ss.str();
}
};
__________________________________________________________________________________________________
8708 kb
static bool _foo = ios::sync_with_stdio(false);
static ostream* _bar = cin.tie(0);
class Solution {
public:
string longestPalindrome(string s) {
if(s.size()<1)
return "";
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);
}
int expandAroundCenter(string &s, int left, int right) {
int L = left, R = right;
while(L>=0 && R<s.size() && s[L]==s[R]) {
L--;
R++;
}
return R-L-1;
}
};
__________________________________________________________________________________________________
8788 kb
class Solution {
public:
string longestPalindrome(string s) {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
std::cout.tie(nullptr);
int l_max = 1;
string sp(s.end()-1,s.end());
int i = 0, j;
while(s.size()-i > l_max)
{
for(j = s.size()-1; j-i+1>=l_max; j--)
{
if( s[i] == s[j] )
{
if(isPalindrome(&s[i],j-i+1))
{
l_max = j-i+1;
sp = s.substr(i,l_max);
break;
}
}
}
i++;
}
return sp;
}
bool isPalindrome(char* s, int sz) {
for(int i=0; i<sz/2; i++)
{
if(s[i] != s[sz-i-1])
return false;
}
return true;
}
};
__________________________________________________________________________________________________