Poj 3080 Blue Jeans + Hdu 2328 Corporate Identity (后缀数组 字典序最小的最长公共子串)

Poj 3080 Blue Jeans

题意：求n个长度为60的字符串的最长连续公共子串，2<=n<=10

1、 最长公共串长度小于3不输出

2、 若出现等长的最长的子串，则输出字典序最小的串

思路：和Poj 3294 Life Forms差不多，只不过变成了只输出第一个。

据说暴力也可以过。。。暴力法参考代码及测试数据：http://blog.csdn.net/lyy289065406/article/details/6647262

尤其注意最后一组测试数据

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))

const int N = int(1e4)+100;

int cmp(int *r,int a,int b,int l){
    return (r[a]==r) && (r[a+l]==r[b+l]);
}
int wa
,wb
,ws
,wv
;
int rank
,height
;

void DA(int *r,int *sa,int n,int m){
    int i,j,p,*x=wa,*y=wb,*t;
    for(i=0;i<m;i++) ws[i]=0;
    for(i=0;i<n;i++) ws[x[i]=r[i]]++;
    for(i=1;i<m;i++) ws[i]+=ws[i-1];
    for(i=n-1;i>=0;i--) sa[--ws[x[i]]]=i;
    for(j=1,p=1;p<n;j*=2,m=p)
    {
        for(p=0,i=n-j;i<n;i++) y[p++]=i;
        for(i=0;i<n;i++) if(sa[i]>=j) y[p++]=sa[i]-j;
        for(i=0;i<n;i++) wv[i]=x[y[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--) sa[--ws[wv[i]]]=y[i];
        for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1;i<n;i++)
            x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
        //printf("p = %d\n", p );
    }
}
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 data
,loc
,sa
,temp
;
int n,q,ans
,id;
char str[105];  
bool vis[105];

bool Judge (int x)
{
	int i,j;
	bool flag=false;
	for (i=1;i<=n;i++)
	{
		int cnt=0;
		int L=i;
		while (L<=n && height[L]<x)
			L++;
		if (L>n) break;
		int R=L;
		while (R<=n && height[R]>=x)
			R++;
		memset(vis,false,sizeof(vis));
		for (j=L-1;j<=R-1;j++)
			if (loc[sa[j]]!=-1)
				vis[loc[sa[j]]]=true;
		for (j=1;j<=q;j++)
			if (vis[j])
				cnt++;
		if (cnt==q)
			if (flag)
				ans[++id]=sa[L-1];
			else
			{
				ans[id=1]=sa[L-1];
				flag=true;
			}
		i=R;
	}
	return flag;
}

void Input ()
{
	int i,de=170;//分隔符
	n=0;
	scanf("%d",&q);
	memset(data,0,sizeof(data));
	for (int id=1;id<=q;id++)
	{
		scanf("%s",str);
		int len=strlen(str);
		for (i=0;i<len;i++)
		{
			loc
=id;
			data[n++]=(int)str[i];
		}
		loc
=-1;
		data[n++]=de++;   //注意分隔符需变化
	}
	data
=0;
}

int main ()
{
#ifdef ONLINE_JUDGE
#else
	freopen("read.txt","r",stdin);
#endif
	int T;
	scanf("%d",&T);
	for (int Cas=1;Cas<=T;Cas++)
	{
		Input ();
		DA(data,sa,n+1,300);
		calheight(data,sa,n);
		int low=0,high=n,mid,res=0;
		while (low<high)
		{
			mid = (low+high)>>1;
			if (Judge(mid))
				res=mid,low=mid+1;
			else 
				high=mid;
		}
		if (res<3)
			printf("no significant commonalities\n");
		else
		{
			int k=ans[1]; //字典序最小一定第一个
			for (int j=0;j<res;j++)   //res子串长度
				printf("%c",(char)data[k+j]);
			printf("\n");
		} 
	}
	return 0;
}

[b]Hdu 2328 Corporate Identity

和上面那题基本一样。

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))

const int N = int(8e5)+100;

int cmp(int *r,int a,int b,int l){
    return (r[a]==r[b]) && (r[a+l]==r[b+l]);
}
int wa
,wb
,ws
,wv
;
int rank
,height
;

void DA(int *r,int *sa,int n,int m){
    int i,j,p,*x=wa,*y=wb,*t;
    for(i=0;i<m;i++) ws[i]=0;
    for(i=0;i<n;i++) ws[x[i]=r[i]]++;
    for(i=1;i<m;i++) ws[i]+=ws[i-1];
    for(i=n-1;i>=0;i--) sa[--ws[x[i]]]=i;
    for(j=1,p=1;p<n;j*=2,m=p)
    {
        for(p=0,i=n-j;i<n;i++) y[p++]=i;
        for(i=0;i<n;i++) if(sa[i]>=j) y[p++]=sa[i]-j;
        for(i=0;i<n;i++) wv[i]=x[y[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--) sa[--ws[wv[i]]]=y[i];
        for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1;i<n;i++)
            x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
        //printf("p = %d\n", p );
    }
}
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 data
,loc
,sa
;
int n,q,id,start;
char str[205];  
bool vis[4005];

bool Judge (int x)
{
	int i,j;
	bool flag=false;
	for (i=1;i<=n;i++)
	{
		int cnt=0;
		int L=i;
		while (L<=n && height[L]<x)
			L++;
		if (L>n) break;
		int R=L;
		while (R<=n && height[R]>=x)
			R++;
		memset(vis,false,sizeof(vis));
		for (j=L-1;j<=R-1;j++)
			if (loc[sa[j]]!=-1)
				vis[loc[sa[j]]]=true;
		for (j=1;j<=q;j++)
			if (vis[j])
				cnt++;
		if (cnt==q)
        {
            start=sa[L-1];
            return true;
        }
		i=R;
	}
	return false;
}

void Input ()
{
	int i,de=170;//分隔符
	n=0;
	memset(data,0,sizeof(data));
	for (int id=1;id<=q;id++)
	{
		scanf("%s",str);
		int len=strlen(str);
		for (i=0;i<len;i++)
		{
			loc
=id;
			data[n++]=(int)str[i];
		}
		loc
=-1;
		data[n++]=de++;   //注意分隔符需变化
	}
	data
=0;
	DA(data,sa,n+1,++de);  //分隔符可能很大
	calheight(data,sa,n);
}

int main ()
{
#ifdef ONLINE_JUDGE
#else
	freopen("read.txt","r",stdin);
#endif
	while (~scanf("%d",&q),q)
	{
		Input ();
		int low=0,high=n,mid,res=0;
		while (low<high)
		{
			mid = (low+high)>>1;
			if (Judge(mid))
				res=mid,low=mid+1;
			else 
				high=mid;
		}
		if (res==0)
			printf("IDENTITY LOST\n");
		else
		{
			int k=start;
			for (int j=0;j<res;j++)   //res子串长度
				printf("%c",(char)data[k+j]);
			printf("\n");
		} 
	}
	return 0;
}