HDU 4681 String

String

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)
Total Submission(s): 158    Accepted Submission(s): 69

Problem Description

Given 3 strings A, B, C, find the longest string D which satisfy the following rules:
a) D is the subsequence of A
b) D is the subsequence of B
c) C is the substring of D
Substring here means a consecutive subsequnce.
You need to output the length of D.

 

 

Input

The first line of the input contains an integer T(T = 20) which means the number of test cases.
For each test case, the first line only contains string A, the second line only contains string B, and the third only contains string C.
The length of each string will not exceed 1000, and string C should always be the subsequence of string A and string B.
All the letters in each string are in lowercase.

 

 

Output

For each test case, output Case #a: b. Here a means the number of case, and b means the length of D.

 

 

Sample Input

2 aaaaa aaaa aa abcdef acebdf cf

 

 

Sample Output

Case #1: 4 Case #2: 3

Hint

For test one, D is "aaaa", and for test two, D is "acf".

 

 

Source

2013 Multi-University Training Contest 8

 

 

Recommend

zhuyuanchen520

 

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;

const int N=1100;

char a[N],b[N],c[N];
int dp1[N][N],dp2[N][N],loc[N<<2][2],cnt;   //dp1[][]表示字符串a，b从前往后的最大公共子串，dp2[][]表示字符串a，b从后往前的最大公共子串
                        //loc[][]记录字符串c在a，b中出现的第一个位置和最后一个位置
int len1,len2,len3;

void solve(char *str,int len){  //求出loc[][]
    int i,j,k;
    for(i=1;i<=len;i++){
        if(str[i]==c[1]){
            for(j=i,k=1;j<=len && k<=len3;j++)
                if(str[j]==c[k])
                    k++;
            if(k!=len3+1)
                break;
            loc[cnt][0]=i;
            loc[cnt][1]=j-1;
            cnt++;
        }
    }
}

int main(){

    //freopen("input.txt","r",stdin);

    int t,cases=0;
    scanf("%d",&t);
    while(t--){
        scanf("%s%s%s",a+1,b+1,c+1);
        len1=strlen(a+1);
        len2=strlen(b+1);
        len3=strlen(c+1);
        memset(dp1,0,sizeof(dp1));
        for(int i=1;i<=len1;i++)
            for(int j=1;j<=len2;j++)
                if(a[i]==b[j])
                    dp1[i][j]=dp1[i-1][j-1]+1;
                else
                    dp1[i][j]=max(dp1[i-1][j],dp1[i][j-1]);

        memset(dp2,0,sizeof(dp2));
        for(int i=len1;i>=1;i--)
            for(int j=len2;j>=1;j--)
                if(a[i]==b[j])
                    dp2[i][j]=dp2[i+1][j+1]+1;
                else
                    dp2[i][j]=max(dp2[i+1][j],dp2[i][j+1]);

        cnt=0;
        solve(a,len1);
        int x=cnt;
        solve(b,len2);
        int y=cnt-x,ans=0;
        for(int i=0;i<x;i++)
            for(int j=0;j<y;j++)
                ans=max(ans,dp1[loc[i][0]-1][loc[j+x][0]-1]+dp2[loc[i][1]+1][loc[j+x][1]+1]);
        printf("Case #%d: %d\n",++cases,ans+len3);
    }
    return 0;
}