SPOJ1812 LCS2(SAM)

2012-11-26 20:30882人阅读评论(15)收藏举报

转载请注明出处，谢谢http://blog.csdn.net/ACM_cxlove?viewmode=contents    by---cxlove 

题目：求多个串的LCS

http://www.spoj.pl/problems/LCS2/

先将一个串建SAM，然后用后面的串去匹配，对于每一个串，保存最大值，对于不同的串，更新最小值。

SAM结点多两个值，ml表示多个串的最小值，nl表示当前串匹配的最大值。

对于SAM初学，要深刻理解出现次数向父亲传递，接收串数从儿子获取这句话。

 

#include<iostream>#include<cstdio>#include<map>#include<cstring>#include<cmath>#include<vector>#include<algorithm>#include<set>#include<string>#include<queue>#define inf 100000005#define M 40#define N 200015#define maxn 300005#define eps 1e-10#define zero(a) fabs(a)<eps#define Min(a,b) ((a)<(b)?(a):(b))#define Max(a,b) ((a)>(b)?(a):(b))#define pb(a) push_back(a)#define mp(a,b) make_pair(a,b)#define mem(a,b) memset(a,b,sizeof(a))#define LL unsigned long long#define MOD 1000000007#define lson step<<1#define rson step<<1|1#define sqr(a) ((a)*(a))#define Key_value ch[ch[root][1]][0]#define test puts("OK");#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;struct SAM{    SAM *pre,*son[26];    int len,nl,ml;}*root,*tail,que[N],*b[N];int tot=0;char str[N/2];int cnt[N/2];void add(int c,int l){    SAM *p=tail,*np=&que[tot++];    np->len=np->ml=l;tail=np;    while(p&&p->son[c]==NULL) p->son[c]=np,p=p->pre;    if(p==NULL) np->pre=root;    else    {        SAM *q=p->son[c];        if(p->len+1==q->len) np->pre=q;        else        {            SAM *nq=&que[tot++];            *nq=*q;            nq->len=nq->ml=p->len+1;            np->pre=q->pre=nq;            while(p&&p->son[c]==q) p->son[c]=nq,p=p->pre;        }    }}int main(){   // freopen("1.in","r",stdin);    tail=root=&que[tot++];    scanf("%s",str);int l=strlen(str);    for(int i=0;str[i];i++) add(str[i]-'a',i+1);    for(int i=0;i<tot;i++) cnt[que[i].len]++;    for(int i=1;i<=l;i++) cnt[i]+=cnt[i-1];    for(int i=0;i<tot;i++) b[--cnt[que[i].len]]=&que[i];    while(scanf("%s",str)!=EOF)    {        SAM *p=root;        for(int i=0,l=0;str[i];i++)        {            int c=str[i]-'a';            if(p->son[c]) {l++;p=p->son[c];}            else            {                while(p&&p->son[c]==NULL) p=p->pre;                if(p==NULL) {l=0;p=root;}                else {l=p->len+1;p=p->son[c];}            }            if(l>p->nl) p->nl=l;        }        for(int i=tot-1;i>=0;i--)        {            p=b[i];            if(p->nl<p->ml) p->ml=p->nl;            if(p->pre&&p->pre->nl<p->nl) p->pre->nl=p->nl;            p->nl=0;        }    }    int ans=0;    for(int i=0;i<tot;i++) if(que[i].ml>ans) ans=que[i].ml;    printf("%d\n",ans);    return 0;}

 错误代码~~~~

#include <iostream>#include <cstdio>#include <cstring>using namespace std;#define maxn 250080#define inf 0x3f3f3f3fchar str[maxn];struct SAM{    SAM *pre,*son[26];    int len;int cslen[20];}que[maxn<<1],*root,*tail,*b[maxn<<1];int tot;int C[maxn<<1];void add(int c,int l){    SAM *p=tail,*np=&que[tot++];    np->len=l;tail=np;    while(p&&p->son[c]==NULL) p->son[c]=np,p=p->pre;    if(p==NULL) {np->pre=root;}    else    {        SAM *q=p->son[c];        if(p->len+1==q->len) {np->pre=q;}        else        {            SAM *nq=&que[tot++];            *nq=*q;            nq->len=p->len+1;            np->pre=q->pre=nq;            while(p&&p->son[c]==q) p->son[c]=nq,p=p->pre;        }    }}void init(int n){tot = 0;for(int i = 0;i < n;i++){que[i].pre = NULL;for(int j = 0;j < 26;j++){que[i].son[j] = NULL;}//memset(que[i].son,0,sizeof(que[i].son));memset(que[i].cslen,0,sizeof(que[i].cslen));}root = tail = &que[tot++];memset(C,0,sizeof(C));}inline int max(int a,int b){return a>b?a:b;}inline int min(int a,int b){return a>b?b:a;}int main(){//freopen("in.txt","r",stdin);while(scanf("%s",&str)!=EOF){int len = strlen(str);init(len<<1);for(int i = 0;i < len;i++){add(str[i]-'a',i+1);}for(int i = 0;i < tot;i++)C[que[i].len]++;for(int i = 1;i <= len;i++)C[i] += C[i-1];for(int i = 0;i < tot;i++)b[--C[que[i].len]] = &que[i];int cnt = 0;while(scanf("%s",str)!=EOF){cnt++;len = strlen(str);SAM * now = root;int tmp = 0;for(int i = 0;i < len;i++){int id = str[i] - 'a';if(now -> son[id]){tmp++;now = now -> son[id];}else{while(now && now -> son[id] == NULL)now = now -> pre;if(now){tmp = now -> len + 1;now = now -> son[id];}else{tmp = 0;now = root;}}now -> cslen[cnt] = max(tmp,now -> cslen[cnt]);}for(int i = tot-1;i >= 0;i--){if(b[i] -> pre)b[i] -> pre -> cslen[cnt] = max(b[i] -> cslen[cnt],b[i] -> pre -> cslen[cnt]);}}int ans = 0;for(int i = 0;i < tot;i++){int fuck = inf;for(int j = 1;j <= cnt;j++){fuck = min(fuck,que[i].cslen[j]);}ans = max(ans,fuck);}if(ans == inf) ans = 0;printf("%d\n",ans);}return 0;}

 

#include <iostream>#include <cstdio>#include <cstring>using namespace std;#define maxn 250080#define inf 0x3f3f3f3fchar str[maxn];struct SAM{    SAM *pre,*son[26];    int len,nl,ml;}que[maxn<<1],*root,*tail,*b[maxn<<1];int tot;int C[maxn<<1];void add(int c,int l){    SAM *p=tail,*np=&que[tot++];    np->len=np->ml=l;tail=np;    while(p&&p->son[c]==NULL) p->son[c]=np,p=p->pre;    if(p==NULL) {np->pre=root;}    else    {        SAM *q=p->son[c];        if(p->len+1==q->len) {np->pre=q;}        else        {            SAM *nq=&que[tot++];            *nq=*q;            nq->len=nq->ml=p->len+1;            np->pre=q->pre=nq;            while(p&&p->son[c]==q) p->son[c]=nq,p=p->pre;        }    }}void init(int n){tot = 0;for(int i = 0;i < n;i++){que[i].nl = 0;que[i].pre = NULL;for(int j = 0;j < 26;j++){que[i].son[j] = NULL;}//memset(que[i].son,0,sizeof(que[i].son));}root = tail = &que[tot++];memset(C,0,sizeof(C));}inline int max(int a,int b){return a>b?a:b;}inline int min(int a,int b){return a>b?b:a;}int main(){//freopen("in.txt","r",stdin);while(scanf("%s",&str)!=EOF){int len = strlen(str);init(len<<1);for(int i = 0;i < len;i++){add(str[i]-'a',i+1);}for(int i = 0;i < tot;i++)C[que[i].len]++;for(int i = 1;i <= len;i++)C[i] += C[i-1];for(int i = 0;i < tot;i++)b[--C[que[i].len]] = &que[i];while(scanf("%s",str)!=EOF){len = strlen(str);SAM * now = root;int tmp = 0;for(int i = 0;i < len;i++){int id = str[i] - 'a';if(now -> son[id]){tmp++;now = now -> son[id];}else{while(now && now -> son[id] == NULL)now = now -> pre;if(now){tmp = now -> len + 1;now = now -> son[id];}else{tmp = 0;now = root;}}now -> nl = max(tmp,now -> nl);}for(int i = tot-1;i >= 0;i--){if(b[i] -> ml > b[i] -> nl)b[i] -> ml = b[i] -> nl;if(b[i] -> pre)b[i] -> pre -> nl = max(b[i] -> nl,b[i] -> pre -> nl);b[i] -> nl = 0;}}int ans = 0;for(int i = 0;i < tot;i++){ans = max(ans,b[i] -> ml);}if(ans == inf) ans = 0;printf("%d\n",ans);}return 0;}