【luogu3856】【TJOI2008】公共子串 [动态规划]

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define rg register
 4 const int N=100+5,inf=0x3f3f3f3f;
 5 int n=0,la,lb,lc;
 6 char a[N],b[N],c[N];
 7 long long las[4][‘z‘+5],f[N][N][N];
 8 
 9 template<class t>void rd(t &x)
10 {
11     x=0;int w=0;char ch=0;
12     while(!isdigit(ch)) w|=ch==‘-‘,ch=getchar();
13     while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
14     x=w?-x:x;
15 }
16 
17 
18 int main()
19 {
20 //    freopen("in.txt","r",stdin);
21     scanf("%s%s%s",a,b,c);
22     la=strlen(a),lb=strlen(b),lc=strlen(c);
23     for(rg int i=0;i<la;++i)
24     {
25         las[1][a[i]]=i+1;memset(las[2],0,sizeof(las[2]));
26         for(rg int j=0;j<lb;++j)
27         {
28             las[2][b[j]]=j+1;memset(las[3],0,sizeof(las[3]));
29             for(rg int k=0;k<lc;++k)
30             {
31                 las[3][c[k]]=k+1;
32                 for(rg int x=‘a‘;x<=‘z‘;++x)
33                 {
34                     int aa=las[1][x],bb=las[2][x],cc=las[3][x];
35                     if(!aa||!bb||!cc) continue;
36                     f[i+1][j+1][k+1]+=f[aa-1][bb-1][cc-1]+1;
37                 }
38             }
39         }
40     }
41     printf("%lld",f[la][lb][lc]);
42     return 0; 
43 }