最长公共子序列LCS

/* Returns length of LCS for X[0..m-1], Y[0..n-1] */int lcs( char *X, char *Y, int m, int n ){    int L[m+1][n+1];    int i, j;    /* Following steps build L[m+1][n+1] in bottom up fashion. Note       that L[i][j] contains length of LCS of X[0..i-1] and Y[0..j-1] */    for (i=0; i<=m; i++)    {        for (j=0; j<=n; j++)        {            if (i == 0 || j == 0)                L[i][j] = 0;            else if (X[i-1] == Y[j-1])                L[i][j] = L[i-1][j-1] + 1;            else                L[i][j] = max(L[i-1][j], L[i][j-1]);        }    }    /* L[m][n] contains length of LCS for X[0..n-1] and Y[0..m-1] */    return L[m][n];}