KMP变形

自己发明的KMP，蜜汁操作和书上不太一样，过了HDU两道题，应该没错。

  1 #include<bits/stdc++.h>
  2 #define ll long long 
  3 #define scan(i) scanf("%d",&i)
  4 #define scand(i) scanf("%lf",&i)
  5 #define scanl(i) scanf("%lld",&i)
  6 #define scans(i) scanf("%s",i) 
  7 #define f(i,a,b) for(int i=a;i<=b;i++) 
  8 #define pb(i) push_back(i)
  9 #define ppb pop_back()
 10 #define pf printf
 11 #define dbg(args...) cout<<#args<<" : "<<args<<endl;
 12 #define input freopen("in.txt","r",stdin)
 13 #define output freopen("out.txt","w",stdout)
 14 #define io ios::sync_with_stdio(0)
 15 using namespace std;
 16 int t,n; 
 17 const int maxn=1000005;
 18 char ss1[maxn],ss2[maxn];
 19 int nxt[maxn];
 20 int nxt2[maxn];
 21 vector<int> ans;
 22 void getnxt(char s[],int nxt[]){
 23     int len=strlen(s+1);
 24     nxt[1]=0;
 25     int p=1;
 26     int k=0;
 27     while(p<=len){
 28         if(k==0){
 29             nxt[p]=k;
 30             p++;
 31             k++;
 32         }
 33         else if(s[k]==s[p]){
 34             nxt[p]=k;
 35             p++;
 36             k++;
 37         }
 38         else k=nxt[k];
 39     }
 40 }
 41 void getnxt2(char s[],int nxt[],int nxt2[]){
 42     getnxt(s,nxt);
 43     int len=strlen(s+1);
 44     f(i,1,len){
 45         nxt2[i]=nxt[i-1]+1;
 46         if(s[i]==nxt2[i]){
 47             nxt2[i]=nxt2[nxt2[i]];
 48         }
 49     }
 50 }
 51 int kmp(char s1[],char s2[]){
 52     int cnt=0;
 53     getnxt(s2,nxt);
 54     int len1=strlen(s1+1);
 55     int len2=strlen(s2+1);
 56     int p1=1;
 57     int p2=1;
 58     while(p2<=len2){
 59         if(s1[p1]==s2[p2]){
 60             p1++;
 61             p2++;
 62         }
 63         else{
 64             if(p1==1) p2++;
 65             else p1=nxt[p1-1]+1;
 66         }
 67         if(p1==len1+1){
 68             cnt++;
 69             nxt[len1]+1;
 70         }
 71     }
 72     return cnt;
 73 }
 74 int kmp2(char s1[],char s2[]){
 75     int cnt=0;
 76     getnxt2(s2,nxt,nxt2);
 77     int len1=strlen(s1+1);
 78     int len2=strlen(s2+1);
 79     int p1=1;
 80     int p2=1;
 81     while(p2<=len2){
 82         if(s1[p1]==s2[p2]){
 83             p1++;
 84             p2++;
 85         }
 86         else{
 87             if(p1==1) p2++;
 88             else p1=nxt2[p1];
 89         }
 90         
 91         if(p1==len1+1){
 92             cnt++;
 93             p1=nxt[len1]+1;
 94         }
 95     }
 96     return cnt;
 97 }
 98 int main(){
 99     scan(t);
100     f(i,1,t){
101         scanf("%s",ss1+1);
102         scanf("%s",ss2+1);
103         pf("%d\n",kmp(ss1,ss2));
104     }
105 }

 

posted @ 2020-10-08 20:17  Lovaer  阅读(228)  评论(0)    收藏  举报