hdu 1503 最长公共子序列

 /*
 给两个串a,b。输出一个最短的串(含等于a的子序列且含等于b的子序列)
 */
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 using namespace std;

 const int maxn=;
 int dp[maxn][maxn],path[maxn][maxn];
 int len,len1,len2;
 char text[maxn],a[maxn],b[maxn];

 void getpath()
 {
     int n=len,i=len1,j=len2;
     while(n)
     {
         if(path[i][j]==)
             text[n--]=a[i],i--,j--;
         else if(path[i][j]==) i--;
         else j--;
     }
 }

 int main()
 {
     int i,j,k;
     a[]=b[]='';
     while(~scanf("%s%s",a+,b+))
     {
         memset(dp,,sizeof(dp));
         len1=strlen(a)-,len2=strlen(b)-;
         for(i=;i<=len1;i++)
         {
             for(j=;j<=len2;j++)
             {
                 if(a[i]==b[j])dp[i][j]=dp[i-][j-]+,path[i][j]=;
                 else
                 {
                     if(dp[i-][j]>dp[i][j-]) dp[i][j]=dp[i-][j],path[i][j]=;
                     else dp[i][j]=dp[i][j-],path[i][j]=;
                 }
             }
         }
         len=dp[len1][len2];
         getpath();
         j=,k=;
         for(i=;i<=len;i++)
         {
             while(a[j]!=text[i]) printf("%c",a[j++]);
             while(b[k]!=text[i]) printf("%c",b[k++]);
             printf("%c",text[i]);
             j++;k++;
         }
         while(j<=len1) printf("%c",a[j++]);
         while(k<=len2) printf("%c",b[k++]);
         printf("\n");
     }
     return ;
 }