Python3程序：查找具有相同左右旋转的最长子序列

def getSubs(alpha):
    allSubs = ['']
    for ch in alpha:
        # Create a copy of the array containing all subsequences
        temp = allSubs[:]
        # Append character to each subsequence of the array to generate new subsequences
        for subseq in temp:
            allSubs.append(subseq + ch)
    return allSubs
def maxSubSeqLen(alpha):
    maxLen = -1
    str_len = len(alpha)
    allSubs = getSubs(alpha)  
    # Traverse all subsequences
    for subseq in allSubs:
        # check if the subsequence has the same left and right rotation
        if subseq[1:] + subseq[:1] == subseq[str_len - 2:] + subseq[:str_len - 2]:
            maxLen = max(maxLen, len(subseq))
    # Return the answer
    return maxLen
alpha = "1919019"
print("The maximum length of subsequence having the same left and right rotations is - ")
print(maxSubSeqLen(alpha))

def maxSubSeqLen(alpha):
    # Length of the string
    str_len = len(alpha)
    maxLen = -1
    # Travere the string
    for p in range(10):
        for q in range(10):
            currMax, isSecond = 0, 0
            # Find an alternate combination of p and q
            for k in range(str_len):
                # Finding the p
                if (isSecond == 0 and ord(alpha[k]) - ord('0') == p):
                    isSecond = 1
                    # Increase the current value by 1
                    currMax += 1
                # Finding q
                elif (isSecond == 1 and ord(alpha[k]) - ord('0') == q):
                    isSecond = 0
                    # Increase the current value by 1
                    currMax += 1
            # For odd length of resultant subsequence.
            if p != q and currMax % 2 == 1:
                # Decrease the value of currMax by 1
                currMax -= 1
            # Get maximum length
            maxLen = max(currMax, maxLen)
    # Return the answer
    return maxLen
# Driver code
alpha = "700980503"
print("The maximum length of subsequence having the same left and right rotations is - ")
print(maxSubSeqLen(alpha))