URAL 1517 Freedom of Choice (后缀数组 输出两个串最长公共子串)
题意:给出两个串的长度(一样长),输出它们的随意一个最长公共子串
#include <cstdio> #include <cstring> #define max(a,b) ((a)>(b)?(a):(b)) #define min(a,b) ((a)<(b)?(a):(b)) const int N = int(2e5)+10; //两个串的总长 #define F(x) ((x)/3+((x)%3==1?0:tb)) #define G(x) ((x)<tb?(x)*3+1:((x)-tb)*3+2) int wa[N],wb[N],wv[N],ws[N]; int c0 (int *r,int a,int b){ return r[a]==r[b] && r[a+1]==r[b+1] && r[a+2]==r[b+2]; } int c12 (int k,int *r,int a,int b){ if (k==2) return r[a]<r[b] || r[a]==r[b] && c12(1,r,a+1,b+1); else return r[a]<r[b] || r[a]==r[b] && wv[a+1]<wv[b+1]; } void sort (int *r,int *a,int *b,int n,int m){ int i; for(i=0;i<n;i++) wv[i]=r[a[i]]; for(i=0;i<m;i++) ws[i]=0; for(i=0;i<n;i++) ws[wv[i]]++; for(i=1;i<m;i++) ws[i]+=ws[i-1]; for(i=n-1;i>=0;i--) b[--ws[wv[i]]]=a[i]; } void DC3 (int *r,int *sa,int n,int m){ int i,j,*rn=r+n,*san=sa+n,ta=0,tb=(n+1)/3,tbc=0,p; r[n]=r[n+1]=0; for(i=0;i<n;i++) if(i%3!=0) wa[tbc++]=i; sort(r+2,wa,wb,tbc,m); sort(r+1,wb,wa,tbc,m); sort(r,wa,wb,tbc,m); for(p=1,rn[F(wb[0])]=0,i=1;i<tbc;i++) rn[F(wb[i])]=c0(r,wb[i-1],wb[i])?p-1:p++; if(p<tbc) DC3(rn,san,tbc,p); else for(i=0;i<tbc;i++) san[rn[i]]=i; for(i=0;i<tbc;i++) if(san[i]<tb) wb[ta++]=san[i]*3; if(n%3==1) wb[ta++]=n-1; sort(r,wb,wa,ta,m); for(i=0;i<tbc;i++) wv[wb[i]=G(san[i])]=i; for(i=0,j=0,p=0;i<ta && j<tbc;p++) sa[p]=c12(wb[j]%3,r,wa[i],wb[j])?
wa[i++]:wb[j++]; for(;i<ta;p++) sa[p]=wa[i++]; for(;j<tbc;p++) sa[p]=wb[j++]; } int rank[N],height[N],sa[3*N],data[3*N]; void calheight(int *r,int *sa,int n){ // memset(height,0,sizeof(height)); // memset(rank,0,sizeof(rank)); int i,j,k=0; for(i=1;i<=n;i++) rank[sa[i]]=i; for(i=0;i<n; height[rank[i++]] = k ) for(k?k--:0,j=sa[rank[i]-1]; r[i+k]==r[j+k]; k++); } int n1,n2; char str[N<<1]; bool Judge (__int64 a,__int64 b) { if ((a-n1)*(b-n1)<0) return true; return false; } void Deal () { int maxn=-1,where=0,i; DC3(data,sa,n1+n2+2,'z'+1); calheight(data,sa,n1+n2+1); for (i=2;i<=n1+n2+1;i++) if (Judge(sa[i-1],sa[i]) && height[i]>maxn) { maxn=height[i]; where=sa[i]; } for (i=0;i<maxn;i++) str[i]=data[where+i]; str[i]=0; printf("%s\n",str); } int main () { scanf("%d",&n1); n2=n1; scanf("%s",str); int i; for (i=0;i<n1;i++) data[i]=(int)str[i]; data[i]=1; //不同于串中字符的分隔符 scanf("%s",str); for (i=0;i<n2;i++) data[n1+1+i]=(int)str[i]; data[n1+1+i]=0; Deal(); return 0; }
posted on 2019-05-15 21:54 xfgnongmin 阅读(134) 评论(0) 编辑 收藏 举报