模板：LCS（最长公共子序列）

 1 #include <cstring>

 2 

 3 #define max(a,b) ((a) > (b) ? (a) : (b))

 4 

 5 int same(char ch1,char ch2)

 6 {

 7     if(ch1 == ch2) return 1;

 8     else return 0;

 9 }

10 

11 int LCS(char *str1,char *str2,int len1,int len2)

12 {

13     int i,j;

14 

15     if(len1 < len2) {char *str3 = str1;str1 = str2;str2 = str3;}

16 

17     int **dp = new int*[2];

18     for(i = 0; i < 2; ++i) dp[i] = new int[len2 + 1];

19     memset(dp[0],0,sizeof(int) * (len2 + 1));

20     dp[1][0] = 0;

21 

22     

23     for(i = 1; i <= len1; ++i)

24     {

25         for(j = 1; j <= len2; ++j)

26         {

27             dp[i % 2][j] = max(dp[(i - 1) % 2][j],max(dp[i % 2][j - 1],dp[(i - 1) % 2][j - 1] + same(str1[i - 1],str2[j - 1])));

28             //cout<<"dp[" << i << "][" << j << "]=" << dp[i % 2][j] << endl;

29         }

30     }

31     int max = dp[len1 % 2][len2];

32 

33     for(i = 0; i < 2; ++i) delete [] dp[i];

34     delete [] dp;

35 

36     return max;

37 }