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====== $exKMP$ ======
===== 算法思想 =====
$exKMP$ 可以求得模式串和文本串的后缀的最长公共前缀
$z$ 数组是自己的后缀和自己的最长公共前缀
$extend$ 数组是文本串的后缀和模式串的最长公共前缀
这里 $s$ 是文本串, $t$ 是模式串
===== 代码实现 =====
#include
using namespace std;
const int maxn=20000100;
char s[maxn],t[maxn];
int lens,lent,z[maxn],extend[maxn];
void solve_z(){
z[1]=lent;
for(int i=2,l=0,r=0;i<=lent;i++){
if(i<=r) z[i]=min(z[i-l+1],r-i+1);
while(i+z[i]<=lent&&t[i+z[i]]==t[z[i]+1]) ++z[i];
if(i+z[i]-1>r) l=i,r=i+z[i]-1;
}
long long ans1=0,ans2=0;
for(int i=1;i<=lent;i++) ans1^=1ll*i*(z[i]+1);
}
void exkmp(){
solve_z();
for(int i=1,l=0,r=0;i<=lens;i++){
if(i<=r) extend[i]=min(z[i-l+1],r-i+1);
while(i+extend[i]<=lens&&s[i+extend[i]]==t[extend[i]+1]) ++extend[i];
if(i+extend[i]-1>r) l=i,r=i+extend[i]-1;
}
}
int main(){
scanf("%s%s",s+1,t+1);
lens=strlen(s+1);lent=strlen(t+1);
exkmp();
long long ans1=0,ans2=0;
//for(int i=1;i<=lent;i++) printf("%d\n",z[i]);
//for(int i=1;i<=lens;i++) printf("%d\n",extend[i]);
for(int i=1;i<=lent;i++) ans1^=1ll*i*(z[i]+1);
for(int i=1;i<=lens;i++) ans2^=1ll*i*(extend[i]+1);
printf("%lld\n%lld",ans1,ans2);
return 0;
}
备用:
#include
#define N 1000010
using namespace std;
int q,nxt[N],extend[N];
string s,t;
void getnxt()
{
nxt[0]=t.size();//nxt[0]一定是T的长度
int now=0;
while(t[now]==t[1+now]&&now+1<(int)t.size())now++;//这就是从1开始暴力
nxt[1]=now;
int p0=1;
for(int i=2;i<(int)t.size();i++)
{
if(i+nxt[i-p0]p的情况
while(t[now]==t[i+now]&&i+now<(int)t.size())now++;//暴力
nxt[i]=now;
p0=i;//更新p0
}
}
}
void exkmp()
{
getnxt();
int now=0;
while(s[now]==t[now]&&nowp的情况
while(t[now]==s[i+now]&&now<(int)t.size()&&now+i<(int)s.size())now++;//暴力
extend[i]=now;
p0=i;//更新p0
}
}
}
int main()
{
cin>>s>>t;
exkmp();
int len=t.size();
for(int i=0;i