//普通
void getnext1(char *s)
{
int i = 0,j = -1,len = strlen(s);
ne[0] = -1;
while(i < len)
{
if(j == -1 || s[i] == s[j]) ne[++i] = ++j;
else j = ne[j];
}
}
//加快预处理
void getnext2(char *s)
{
int i = 0,j = -1,len = strlen(s);
ne[0] = -1;
while(i < len)
{
if(j == -1 || s[i] == s[j])
{
if(s[++i] == s[++j]) ne[i] = ne[j];
else ne[i] = j;
}
else j = ne[j];
}
}
//反悔x在y中出现的次数，可以重叠
int kmp(char *x,char *y)
{
getnext1(x);
int i = 0,j = 0,ans = 0,leny = strlen(y),lenx = strlen(x);
while(i < leny)
{
if(j == -1 || x[j] == y[i])
{
i++,j++;
if(j == lenx)
{
ans++;
j = ne[j];
}
}
else j = ne[j];
}
return ans;
}
KMP模版
//求浮动匹配
//l[i]表示i结点之前(包括i结点),小于a[i]的个数
//le[i]表示i结点之前(包括i结点),小于等于a[i]的个数
//l[i] == l[j] && le[i] == le[j],则匹配
#include<bits/stdc++.h>
using namespace std;
int n,k,s,a[100005],b[25005],ne[25005],tree[30],l[100005],le[100005];
inline int lowbit(int x)
{
return x&-x;
}
void update(int pos,int x)
{
while(pos <= s)
{
tree[pos] += x;
pos += lowbit(pos);
}
}
int getsum(int pos)
{
int sum = 0;
while(pos)
{
sum += tree[pos];
pos -= lowbit(pos);
}
return sum;
}
void getnext1()
{
memset(tree,0,sizeof(tree));
int i = 0,j = -1;
ne[0] = -1;
while(i < k)
{
if(j == -1 || getsum(b[i]-1) == l[j] && getsum(b[i]) == le[j])
{
ne[++i] = ++j;
if(i < k) update(b[i],1);
}
else
{
for(int t = i-j;t < i-ne[j];t++) update(b[t],-1);
j = ne[j];
}
}
}
vector<int> kmp()
{
getnext1();
memset(tree,0,sizeof(tree));
vector<int> ans;
int i = 0,j = 0;
update(a[0],1);
while(i < n)
{
if(j == -1 || getsum(a[i]-1) == l[j] && getsum(a[i]) == le[j])
{
i++,j++;
if(i < n) update(a[i],1);
if(j == k)
{
ans.push_back(i-k+1);
for(int t = i-j;t < i-ne[j];t++) update(a[t],-1);
j = ne[j];
}
}
else
{
for(int t = i-j;t < i-ne[j];t++) update(a[t],-1);
j = ne[j];
}
}
return ans;
}
int main()
{
while(~scanf("%d%d%d",&n,&k,&s))
{
memset(tree,0,sizeof(tree));
memset(l,0,sizeof(l));
memset(le,0,sizeof(le));
memset(ne,0,sizeof(ne));
for(int i = 0;i < n;i++) scanf("%d",&a[i]);
for(int i = 0;i < k;i++)
{
scanf("%d",&b[i]);
update(b[i],1);
l[i] = getsum(b[i]-1);
le[i] = getsum(b[i]);
}
vector<int> v = kmp();
printf("%d\n",v.size());
for(int i = 0;i < v.size();i++) printf("%d\n",v[i]);
}
return 0;
}
浮动匹配
void getnext(char *s)
{
int j = 0,len = strlen(s),k = 1;
ne[0] = len;
while(j+1 < len && s[j] == s[j+1]) j++;
ne[1] = j;
for(int i = 2;i < len;i++)
{
if(ne[i-k]+i < ne[k]+k) ne[i] = ne[i-k];
else
{
j = max(0,ne[k]+k-i);
while(i+j < len && s[i+j] == s[j]) j++;
ne[i] = j;
k = i;
}
}
}
void ekmp(char *x,char *y)
{
getnext(x);
int j = 0,lenx = strlen(x),leny = strlen(y);
while(j < lenx && j < leny && x[j] == y[j]) j++;
ex[0] = j;
int k = 0;
for(int i = 1;i < leny;i++)
{
if(ne[i-k]+i < ex[k]+k) ex[i] = ne[i-k];
else
{
j = max(0,ex[k]+k-i);
while(i+j < leny && j < lenx && y[i+j] == x[j]) j++;
ex[i] = j;
k = i;
}
}
}
扩展KMP
//abaa
//i: 0 1 3 4 5 6 7 8 9 10
//a[i]: $ # a # b # a # a #
//p[i]: 1 1 2 1 4 1 2 3 2 1
#include<bits/stdc++.h>
using namespace std;
char s[100005],a[200005];
int p[200005];
void manacher(int len)
{
int mx = 0,id;
for(int i = 1;i < len;i++)
{
if(mx > i) p[i] = min(p[2*id-i],mx-i);
else p[i] = 1;
while(a[i+p[i]] == a[i-p[i]]) p[i]++;
if(p[i]+i > mx)
{
mx = p[i]+i;
id = i;
}
}
}
int main()
{
scanf("%s",s);
a[0] = ‘$‘;
a[1] = ‘#‘;
int len = 2;
for(int i = 0;s[i];i++)
{
a[len++] = s[i];
a[len++] = ‘#‘;
}
manacher(len);
int ans = 0;
for(int i = 0;i < len;i++) ans = max(ans,p[i]);
printf("%d\n",ans-1);
return 0;
}
最长回文字串Manacher
//添加
void add(char *s,int x)
{
int now = 0;
for(int i = 0;i < strlen(s);i++)
{
int c = s[i]-‘a‘;
if(!ch[now][c])
{
ch[now][c] = ++sz;
cnt[sz] = 0;
}
now = ch[now][c];
cnt[now]++;
}
}
//查找数量
int getnum(char *s)
{
int now = 0;
for(int i = 0;i < strlen(s);i++)
{
int c = s[i]-‘a‘;
if(!ch[now][c]) return 0;
now = ch[now][c];
}
return cnt[now];
}
trie树
//HDU2222
//求目标中出现了几个模式串
#include<bits/stdc++.h>
using namespace std;
struct Trie
{
int next[500000][26],fail[500005],num[500005],root,cnt;
int newnode()
{
for(int i = 0;i < 26;i++) next[cnt][i] = -1;
num[cnt++] = 0;
return cnt-1;
}
void init()
{
cnt = 0;
root = newnode();
}
void insert(char *s)
{
int now = root,len = strlen(s);
for(int i = 0;i < len;i++)
{
int c = s[i]-‘a‘;
if(next[now][c] == -1) next[now][c] = newnode();
now = next[now][c];
}
num[now]++;
}
void build()
{
queue<int> q;
fail[root] = root;
for(int i = 0;i < 26;i++)
{
if(next[root][i] == -1) next[root][i] = root;
else
{
fail[next[root][i]] = root;
q.push(next[root][i]);
}
}
while(!q.empty())
{
int now = q.front();
q.pop();
for(int i = 0;i < 26;i++)
{
if(next[now][i] == -1) next[now][i] = next[fail[now]][i];
else
{
fail[next[now][i]] = next[fail[now]][i];
q.push(next[now][i]);
}
}
}
}
int query(char *s)
{
int now = root,ans = 0,len = strlen(s);
for(int i = 0;i < len;i++)
{
now = next[now][s[i]-‘a‘];
int t = now;
while(t != root)
{
ans += num[t];
num[t] = 0;
t = fail[t];
}
}
return ans;
}
void debug()
{
for(int i = 0;i < cnt;i++)
{
printf("id = %3d,fail = %3d,num = %3d,chi = [",i,fail[i],num[i]);
for(int j = 0;j < 26;j++) printf("%2d",next[i][j]);
printf("]\n");
}
}
};
int n;
char s[1000001];
Trie ac;
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
ac.init();
while(n--)
{
scanf("%s",s);
ac.insert(s);
}
ac.build();
scanf("%s",s);
printf("%d\n",ac.query(s));
}
return 0;
}
AC自动机
//O(nlogn)
/待排序数组长度n,放在0~n中，最后补0
//sa[i]:每个后缀串从小到大排第i小的位置
//rank[i]:i位置的从小到大排序位置
//height[i]:sa[i]和sa[i-1]对应后缀的最长公共前缀
//n = 8
//num[i]: 1 1 2 1 1 1 1 2 0 num[8]加0
//sa[i]: 8 3 4 5 0 6 1 7 2 num[0~n]有效
//rank[i]: 4 6 8 1 2 3 5 7 0 num[0~n-1]有效
//height[i]:0 0 3 2 3 1 2 0 1 num[2~n]有效
int t1[N],t2[N],c[N],sa[N],rank[N],height[N];
int mm[200005],best[20][200005],rmq[200005];
int main()
{
gets(s);
int len = strlen(s);
for(int i = 0;i < len;i++) r[i] = s[i];
da(r,sa,rk,height,len,128);
return 0;
}
bool cmp(int *r,int a,int b,int l)
{
return r[a] == r[b] && r[a+l] == r[b+l];
}
void da(int *r,int *sa,int *rank,int *height,int n,int m)
{
r[n] = 0;
n++;
int *x = t1,*y = t2;
for(int i = 0;i < m;i++) c[i] = 0;
for(int i = 0;i < n;i++) c[x[i] = r[i]]++;
for(int i = 1;i < m;i++) c[i] += c[i-1];
for(int i = n-1;i >= 0;i--) sa[--c[x[i]]] = i;
for(int j = 1;j <= n;j <<= 1)
{
int p = 0;
for(int i = n-j;i < n;i++) y[p++] = i;
for(int i = 0;i < n;i++)
{
if(sa[i] >= j) y[p++] = sa[i]-j;
}
for(int i = 0;i < m;i++) c[i] = 0;
for(int i = 0;i < n;i++) c[x[y[i]]]++;
for(int i = 1;i < m;i++) c[i] += c[i-1];
for(int i = n-1;i >= 0;i--) sa[--c[x[y[i]]]] = y[i];
swap(x,y);
p = 1;
x[sa[0]] = 0;
for(int i = 1;i < n;i++) x[sa[i]] = cmp(y,sa[i-1],sa[i],j)?p-1:p++;
if(p >= n) break;
m = p;
}
int k = 0;
n--;
for(int i = 0;i <= n;i++) rank[sa[i]] = i;
for(int i = 0;i < n;i++)
{
if(k) k--;
int t = sa[rank[i]-1];
while(r[i+k] == r[t+k]) k++;
height[rank[i]] = k;
}
}
void initrmq(int n)
{
mm[0] = -1;
for(int i = 1;i < n;i++) mm[i] = (i&(i-1) == 0)?mm[i-1]+1:mm[i-1];
for(int i = 1;i < n;i++) best[0][i] = i;
for(int i = 1;i <= mm[n-1];i++)
{
for(int j = 1;j+(1<<i)-1 < n;j++)
{
int a = best[i-1][j],b = best[i-1][j+(1<<(i-1))];
best[i][j] = rmq[a] < rmq[b]?a:b;
}
}
}
int askrmq(int a,int b)
{
int t = mm[b-a+1];
b -= (1<<t)-1;
a = best[t][a];
b = best[t][b];
return rmq[a] < rmq[b]?a:b;
}
//求a,b位置开始的后缀的最长公共前缀
int lcp(int a,int b)
{
a = rk[a];
b = rk[b];
if(a > b) swap(a,b);
return height[askrmq(a+1,b)];
}
后缀数组DA
//O(n)
//所有数组开3倍
#include<bits/stdc++.h>
#define F(x) ((x)/3+((x)%3 == 1?0:tb))
#define G(x) ((x) < tb?(x)*3+1:((x)-tb)*3+2)
#define N 2005
using namespace std;
int wa[3*N],wb[3*N],wv[3*N],wss[3*N],r[3*N],sa[3*N],rk[3*N],height[3*N];
char s[3*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);
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)
{
for(int i = 0;i < n;i++) wv[i] = r[a[i]];
for(int i = 0;i < m;i++) wss[i] = 0;
for(int i = 0;i < n;i++) wss[wv[i]]++;
for(int i = 1;i < m;i++) wss[i] += wss[i-1];
for(int i = n-1;i >= 0;i--) b[--wss[wv[i]]] = a[i];
}
void dc3(int *r,int *sa,int n,int m)
{
int *rn = r+n,*san = sa+n,ta = 0,tb = (n+1)/3,tbc = 0,i,j,p;
r[n]=r[n+1]=0;
for(i = 0;i < n;i++)
{
if(i%3) 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++];
}
void da(int *r,int *sa,int *rank,int *height,int n,int m)
{
for(int i = n;i < n*3;i++) r[i] = 0;
dc3(r,sa,n+1,m);
int k = 0;
for(int i = 0;i <= n;i++) rank[sa[i]] = i;
for(int i = 0;i < n;i++)
{
if(k) k--;
int t = sa[rank[i]-1];
while(r[i+k] == r[t+k]) k++;
height[rank[i]] = k;
}
}
后缀数组DC3
struct samnode
{
samnode *fa,*next[26];
int len;
void clear()
{
fa = NULL;
len = 0;
memset(next,0,sizeof(next));
}
};
samnode *root,*last,st[2*N];
int sz;
char s[10005];
int topcnt[2*N];
samnode *topsam[2*N];
void saminit()
{
sz = 0;
root = last = &st[sz++];
root ->clear();
}
void samadd(int w)
{
samnode *p = last,*np = &st[sz++];
last = np;
np->clear();
np->len = p->len+1;
while(p && !p->next[w])
{
p->next[w] = np;
p = p->fa;
}
if(!p)
{
np->fa = root;
return;
}
samnode *q = p->next[w];
if(q->len == p->len+1)
{
np->fa = q;
return;
}
samnode *nq = &st[sz++];
nq->clear();
nq->len = p->len+1;
memcpy(nq->next,q->next,sizeof(q->next));
nq->fa = q->fa;
q->fa = nq;
np->fa = nq;
while(p && p->next[w] == q)
{
p->next[w] = nq;
p = p->fa;
}
}
void sambuild(char *s)
{
saminit();
int len = strlen(s);
for(int i = 0;i < len;i++) samadd(s[i]-‘a‘);
}
int main()
{
gets(s);
sambuild(s);
memset(topcnt,0,sizeof(topcnt));
for(int i = 0;i < sz;i++) topcnt[st[i].len]++;
for(int i = 1;i <= strlen(s);i++) topcnt[i] += topcnt[i-1];
for(int i = 0;i < sz;i++) topsam[--topcnt[st[i].len]] = &st[i];
return 0;
}
后缀自动机
#include<bits/stdc++.h>
using namespace std;
const int HASH = 10007;
const int N = 2010;
const int SEED = 13331;
char s[N];
struct HASHMAP
{
int head[N],next[N],size,f[N];
unsigned long long state[N];
void init()
{
size = 0;
memset(state,-1,sizeof(state));
}
int insert(unsigned long long x,int id)
{
int h = x%HASH;
for(int i = head[h];i != -1;i = next[i])
{
if(x == state[i]) return f[i];
}
f[size] = id;
state[size] = x;
next[size] = head[h];
head[h] = size++;
return 0;
}
};
int main()
{
gets(s);
int len = strlen(s);
unsigned long long t = 0;
for(int i = 1;i <= len;i++) t = t*SEED+s[i-1];
}
字符串hash
时间： 2024-10-13 12:48:56