Red Huang

Red Huang

Codeforces Round #201 (Div. 2) D. Lucky Common Subsequence

求出最長子序列,且不包含一個子字串

DP 難題,要在 LCS 上面多開一維的空間

用來記錄病毒字串的生長,所以需要用 KMP

首次深入學習了

//  
//        GGGGGGGGGGGGG        CCCCCCCCCCCCC               AAA  
//     GGG::::::::::::G     CCC::::::::::::C              A:::A  
//   GG:::::::::::::::G   CC:::::::::::::::C             A:::::A  
//  G:::::GGGGGGGG::::G  C:::::CCCCCCCC::::C            A:::::::A  
// G:::::G       GGGGGG C:::::C       CCCCCC           A:::::::::A  
//G:::::G              C:::::C                        A:::::A:::::A  
//G:::::G              C:::::C                       A:::::A A:::::A  
//G:::::G    GGGGGGGGGGC:::::C                      A:::::A   A:::::A  
//G:::::G    G::::::::GC:::::C                     A:::::A     A:::::A  
//G:::::G    GGGGG::::GC:::::C                    A:::::AAAAAAAAA:::::A  
//G:::::G        G::::GC:::::C                   A:::::::::::::::::::::A  
// G:::::G       G::::G C:::::C       CCCCCC    A:::::AAAAAAAAAAAAA:::::A  
//  G:::::GGGGGGGG::::G  C:::::CCCCCCCC::::C   A:::::A             A:::::A  
//   GG:::::::::::::::G   CC:::::::::::::::C  A:::::A               A:::::A  
//     GGG::::::GGG:::G     CCC::::::::::::C A:::::A                 A:::::A  
//        GGGGGG   GGGG        CCCCCCCCCCCCCAAAAAAA                   AAAAAAA  
#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <algorithm>  
#include <cmath>  
#include <climits>  
#include <vector>  
#include <set>  
#include <map>  
#include <queue>  
#include <cctype>  
#include <utility>  
#include <ctime>  
using namespace std;  
#ifdef DEBUG  
#define VAR(a,b) decltype(b) a=(b)  
#define debug(...) printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)  
#define gettime() end\_time=clock();printf("now running time is %.7f\\n",(float)(end\_time - start\_time)/CLOCKS\_PER\_SEC);  
#else  
#define VAR(a,b) \_\_typeof(b) a=(b)  
#define debug(...)  
#define gettime()  
#endif  
typedef unsigned int uint;  
typedef long long int Int;  
typedef unsigned long long int UInt;  
#define Set(a,s) memset(a,s,sizeof(a))  
#define Write(w) freopen(w,"w",stdout)  
#define Read(r) freopen(r,"r",stdin)  
#define Pln() printf("\\n")  
#define I\_de(x,n)for(int i=0;i<n;i++)printf("%d ",x\[i\]);Pln()  
#define De(x)printf(#x"%d\\n",x)  
#define For(i,x)for(int i=0;i<x;i++)  
#define CON(x,y) x##y  
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\\  
    printf("%d ",dp\[htx\]\[hty\]);}Pln();}  
#define M 30005  
#define PII pair<int,int\>  
#define PB push\_back  
#define oo INT\_MAX  
#define Set\_oo 0x3f  
#define FOR(a,b) for(VAR(a,(b).begin());a!=(b).end();++a)  
#define eps 1e-6  
#define X first  
#define Y second  
clock\_t start\_time=clock(), end\_time;  
bool xdy(double x,double y){return x>y+eps;}  
bool xddy(double x,double y){return x>y-eps;}  
bool xcy(double x,double y){return x<y-eps;}  
bool xcdy(double x,double y){return x<y+eps;}  
int min3(int x,int y,int z){  
    int tmp=min(x,y);  
    return min(tmp,z);  
}  
int max3(int x,int y,int z){  
    int tmp=max(x,y);  
    return max(tmp,z);  
}  
  
char virus\[105\],s1\[105\],s2\[105\];  
int dp\[128\]\[128\]\[128\];  
bool vis\[128\]\[128\]\[128\];  
int acpos\[105\]\[128\];  
bool checkac(int pos,int i,char x){  
    if(virus\[pos\]!=x){  
        return false;  
    }  
    for(int j=pos-1;j>=0;j--){  
        i--;  
        if(virus\[j\]!=virus\[i\])return false;  
    }  
    return true;  
}  
void initac(){  
    for(int i=0;virus\[i\];i++){  
        for(int j='A';j<='Z';j++){  
            for(int k=i;k>=0;k--){  
                if(checkac(k,i,j)){  
                    acpos\[i\]\[j\]=k+1;  
                    break;  
                }  
            }  
        }  
    }  
  
}  
int dfs(int pos1,int pos2,int pos3){  
  
    if(!virus\[pos3\])return -oo;  
    if(vis\[pos1\]\[pos2\]\[pos3\])return dp\[pos1\]\[pos2\]\[pos3\];  
    vis\[pos1\]\[pos2\]\[pos3\]=1;  
    if(s1\[pos1\]==0||s2\[pos2\]==0){  
        return 0;  
    }  
    if(s1\[pos1\]==s2\[pos2\]){  
        dp\[pos1\]\[pos2\]\[pos3\]=dfs(pos1+1,pos2+1,acpos\[pos3\]\[s1\[pos1\]\])+1;  
    }  
    dp\[pos1\]\[pos2\]\[pos3\]=max3(dp\[pos1\]\[pos2\]\[pos3\],dfs(pos1+1,pos2,pos3),dfs(pos1,pos2+1,pos3));  
    return dp\[pos1\]\[pos2\]\[pos3\];  
}  
void recon(int pos1,int pos2,int pos3){  
    if(!virus\[pos3\])return;  
    if(s1\[pos1\]==0||s2\[pos2\]==0)return ;  
//    debug("%d %d %d\\n",pos1,pos2,pos3);  
    if(dp\[pos1\]\[pos2\]\[pos3\]==dp\[pos1+1\]\[pos2\]\[pos3\]){  
        recon(pos1+1,pos2,pos3);  
    }else if(dp\[pos1\]\[pos2\]\[pos3\]==dp\[pos1\]\[pos2+1\]\[pos3\]){  
        recon(pos1,pos2+1,pos3);  
    }else{  
        printf("%c",s1\[pos1\]);  
        recon(pos1+1,pos2+1,acpos\[pos3\]\[s1\[pos1\]\]);  
    }  
}  
int main() {  
    ios\_base::sync\_with\_stdio(0);  
    while(~scanf("%s %s %s",s1,s2,virus)){  
        initac();  
        Set(vis,0);  
        if(dfs(0,0,0)==0){  
            puts("0");  
        }else{  
//            printf("%d\\n",dfs(0,0,0));  
            recon(0,0,0);  
            puts("");  
        }  
    }  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
}  

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