Gym 101350I - Mirrored String II ( Manacher马拉车算法 -- 最长回文子串 )
题意
给一个字符串, 求最长回文镜像子串长度
思路
Manacher + 镜像判断
算法实现 : Manacher算法总结
AC代码 ( kuangbin板子 )
#include <iostream>
#include <algorithm> #include <cstdio> #include <cstring> #define mst(a) memset(a,0,sizeof(a)) using namespace std; const int maxn = 1e3+10; int len; char mrk[] = "A HI M O TUVWXY "; char Ma[maxn*2]; int Mp[maxn*2]; void Manacher( char s[], int len ){ int l = 0; Ma[l++] = '$'; Ma[l++] = '#'; for( int i = 0; i < len; i++ ){ Ma[l++] = s[i]; Ma[l++] = '#'; } Ma[l] = 0; int mx = 0, id = 0; for( int i = 0; i < l; i++ ){ Mp[i] = mx > i ? min(Mp[2*id-i], mx-i) : 1; while( Ma[i+Mp[i]] == Ma[i-Mp[i]] && mrk[Ma[i+Mp[i]]-'A'] != ' ' && mrk[Ma[i-Mp[i]]-'A'] != ' ' ) Mp[i]++; if( i+Mp[i] > mx ){ mx = i + Mp[i]; id = i; } } } char s[maxn]; int main() { int T; scanf("%d",&T); while(T--){ mst(s); mst(Ma); mst(Mp); scanf("%s",s); len = strlen(s); Manacher(s, len); int ans = 0; for( int i = 0; i < 2*len+2; i++ ) if( mrk[Ma[i]-'A'] != ' ' ) ans = max(ans, Mp[i]-1); printf("%d\n",ans); } return 0; }
分类:
Manacher
题意
给一个字符串, 求最长回文镜像子串长度
思路
Manacher + 镜像判断
算法实现 : Manacher算法总结
AC代码 ( kuangbin板子 )
#include <iostream>
#include <algorithm> #include <cstdio> #include <cstring> #define mst(a) memset(a,0,sizeof(a)) using namespace std; const int maxn = 1e3+10; int len; char mrk[] = "A HI M O TUVWXY "; char Ma[maxn*2]; int Mp[maxn*2]; void Manacher( char s[], int len ){ int l = 0; Ma[l++] = '$'; Ma[l++] = '#'; for( int i = 0; i < len; i++ ){ Ma[l++] = s[i]; Ma[l++] = '#'; } Ma[l] = 0; int mx = 0, id = 0; for( int i = 0; i < l; i++ ){ Mp[i] = mx > i ? min(Mp[2*id-i], mx-i) : 1; while( Ma[i+Mp[i]] == Ma[i-Mp[i]] && mrk[Ma[i+Mp[i]]-'A'] != ' ' && mrk[Ma[i-Mp[i]]-'A'] != ' ' ) Mp[i]++; if( i+Mp[i] > mx ){ mx = i + Mp[i]; id = i; } } } char s[maxn]; int main() { int T; scanf("%d",&T); while(T--){ mst(s); mst(Ma); mst(Mp); scanf("%s",s); len = strlen(s); Manacher(s, len); int ans = 0; for( int i = 0; i < 2*len+2; i++ ) if( mrk[Ma[i]-'A'] != ' ' ) ans = max(ans, Mp[i]-1); printf("%d\n",ans); } return 0; }