【EXKMP】【2015-2】day1 T3 字符串转换

哈哈这题乱搞骗了个AC~~~~~~



留个字符串hash模板

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;
#define rep(i,l,r) for(int i=(l),_=(r);i<=_;i++)
#define per(i,r,l) for(int i=(r),_=(l);i>=_;i--)
#define MS(arr,x) memset(arr,x,sizeof(arr))
#define INE(i,u) for(int i=head[u];~i;i=e[i].next)
#define LL long long
#define ULL unsigned LL
inline const int read()
{int r=0,k=1;char c=getchar();for(;c<'0'||c>'9';c=getchar())if(c=='-')k=-1;
for(;c>='0'&&c<='9';c=getchar())r=r*10+c-'0';return k*r;}
////////////////////////////////////////////////
const int base=131;
int n;
char a[1000010],b[1000010];
int next[1000010];
int ansl=1,ansr=-1;
ULL ha[1000010],hb[1000010];
ULL pm[1000010];
////////////////////////////////////////////////
ULL hasha(int l,int r)
{
return ha[r]-ha[l-1]*pm[r-l+1];
}
ULL hashb(int l,int r)
{
return hb[l]-hb[r+1]*pm[r-l+1];
}
bool check(int l,int r)
{
int l1=r-l+1,l2=n-r+1,l3=n-l1-l2;
return hasha(r+1,n) == hashb(l1+1,l1+l2-1) && hasha(1,l-1) == hashb(n-l3,n);
}
void init_hash()
{
rep(i,1,n) ha[i]=ha[i-1]*base+a[i];
per(i,n,1) hb[i]=hb[i+1]*base+b[i];
}
void init_next()
{
int j=0;
rep(i,2,n)
{
while(j&&b[i]!=b[j+1]) j=next[j];
next[i]=j+=b[i]==b[j+1];
}
}
void kmp()
{
int j=0;
rep(i,1,n)
{
while(j&&a[i]!=b[j+1]) j=next[j];
j+=a[i]==b[j+1];
int l=i-j+1,r=i;
if(l>ansl || l==ansl&&r<ansr)
{
if(check(l,r))
{
ansl=l;
ansr=r;
}
}
}
}
////////////////////////////////////////////////
void input()
{
gets(a+1); gets(b+1);
n=strlen(a+1);
}
void solve()
{
pm[0]=1; rep(i,1,n) pm[i]=pm[i-1]*base;
init_hash();
init_next();
kmp();
printf("%d %d\n",ansl-2,ansr);
}
////////////////////////////////////////////////
int main()
{
freopen("trans.in","r",stdin); freopen("trans.out","w",stdout);
input(),solve();
return 0;
}

放两个EXKMP代码，慢慢看

#include <map> #include <cmath> #include <cstdio> #include <vector> #include <string> #include <cstdlib> #include <cstring> #include <sstream> #include <fstream> #include <iostream> #include <algorithm> #define PB push_back #define MP make_pair #define BG begin() #define ED end() #define SZ(x) ((int)((x).size())) #define FF first #define SS second #define foreach(i,x) for (__typeof((x).begin()) i=(x).begin();i!=(x).end();i++) #define FOR(i,l,r) for (int i=(l);i<=(r);i++) #define ROF(i,r,l) for (int i=(r);i>=(l);i--) using namespace std; #define N 2010000 char _a ,_b ; int g1 ,g2 ; void cal(string a,int f[]) { f[1]=0; while (a[f[1]]==a[f[1]+1]) f[1]++; int mx=1,n=SZ(a); FOR(i,2,n-1) { if (f[mx]+mx>i) f[i]=min(f[i-mx],f[mx]+mx-i); else f[i]=0; while (a[f[i]]==a[f[i]+i]) f[i]++; if (f[i]+i>f[mx]+mx) mx=i; }; } #define fly "" int main() { freopen("trans"fly".in","r",stdin); freopen("trans"fly".out","w",stdout); gets(_a); gets(_b); string a(_a),b(_b); int n=SZ(a); if (SZ(b)!=n) {puts("-1 -1");return 0;}; string fa(a),fb(b); FOR(i,0,n-1) b[i]=_b[n-i-1]; FOR(i,0,n-1) fa[i]=_a[n-i-1]; cal(fb+a,g1); cal(fa+fb,g2); FOR(i,0,n-1) g1[i]=g1[i+n]; FOR(i,0,n-1) g2[i]=i-g2[2*n-1-i]; ROF(i,n-2,0) g2[i]=min(g2[i],g2[i+1]); int x=-1,y=-1; g1 =0; FOR(i,0,n-2) if (a[i]!=b[i]) break; else { int l=n-1-g1[i+1],r=n-1; if (g2[l]>i) continue; while (l<r) { int mid=(l+r+1)>>1; if (g2[mid]<=i) l=mid; else r=mid-1; }; if (g2[l]<=i) x=i,y=i+n-l; }; printf("%d %d\n",x,y); return 0; }

#include <map>
#include <cmath>
#include <cstdio>
#include <vector>
#include <string>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <fstream>
#include <iostream>
#include <algorithm>
#define PB push_back
#define MP make_pair
#define BG begin()
#define ED end()
#define SZ(x) ((int)((x).size()))
#define FF first
#define SS second
#define foreach(i,x) for (__typeof((x).begin()) i=(x).begin();i!=(x).end();i++)
#define FOR(i,l,r) for (int i=(l);i<=(r);i++)
#define ROF(i,r,l) for (int i=(r);i>=(l);i--)
using namespace std;
#define N 2010000
char _a
,_b
;
int g1
,g2
;

void cal(string a,int f[]) {
f[1]=0;
while (a[f[1]]==a[f[1]+1]) f[1]++;
int mx=1,n=SZ(a);
FOR(i,2,n-1) {
if (f[mx]+mx>i) f[i]=min(f[i-mx],f[mx]+mx-i); else f[i]=0;
while (a[f[i]]==a[f[i]+i]) f[i]++;
if (f[i]+i>f[mx]+mx) mx=i;
};
}

#define fly ""

int main() {
freopen("trans"fly".in","r",stdin);
freopen("trans"fly".out","w",stdout);
gets(_a);
gets(_b);
string a(_a),b(_b);
int n=SZ(a);
if (SZ(b)!=n) {puts("-1 -1");return 0;};
string fa(a),fb(b);
FOR(i,0,n-1) b[i]=_b[n-i-1];
FOR(i,0,n-1) fa[i]=_a[n-i-1];
cal(fb+a,g1);
cal(fa+fb,g2);
FOR(i,0,n-1) g1[i]=g1[i+n];
FOR(i,0,n-1) g2[i]=i-g2[2*n-1-i];
ROF(i,n-2,0) g2[i]=min(g2[i],g2[i+1]);
int x=-1,y=-1;
g1
=0;
FOR(i,0,n-2) if (a[i]!=b[i]) break; else {
int l=n-1-g1[i+1],r=n-1;
if (g2[l]>i) continue;
while (l<r) {
int mid=(l+r+1)>>1;
if (g2[mid]<=i) l=mid; else r=mid-1;
};
if (g2[l]<=i) x=i,y=i+n-l;
};
printf("%d %d\n",x,y);
return 0;
}