Number_of_deletions_to_make_pallindrome.py

# Python3 implementation to find 
# minimum number of deletions
# to make a string palindromic 

INT_MAX = 99999999999
  
def noofDeletions(s): 
  
    # reverse of input string 
    revInput = s[::-1] 
  
    #  DP table for storing   
    # edit distance of string and reverse. 
    n = len(s) 
    dp = [[-1 for _ in range(n + 1)]  
              for __ in range(n + 1)] 
    for i in range(n + 1): 
        dp[0][i] = i 
        dp[i][0] = i 
  
    # Find edit distance between  
    # input and revInput considering 
    # only delete operation. 
    for i in range(1, n + 1): 
        for j in range(1, n + 1): 
            if s[i - 1] == revInput[j - 1]: 
                dp[i][j] = dp[i - 1][j - 1] 
            else: 
                dp[i][j] = 1 + min(dp[i - 1][j],  
                                   dp[i][j - 1]) 
  
    # Go from bottom left to top right 
    # and find the minimum 
    res = INT_MAX 
    i, j = n, 0
    while i >= 0: 
        res = min(res, dp[i][j]) 
        if i < n: 
            res = min(res, dp[i + 1][j]) 
        if i > 0: 
            res = min(res, dp[i - 1][j]) 
        i -= 1
        j += 1
    return res
  
# Driver Code 
if __name__ == "__main__": 
    string = input('Enter string: ')
    print(noofDeletions(string)) 

# Time Complexity: O(n*n)
# Space complexity: O(n*n)

# Example 1: 
# input : malasiyala
# output: 3

# Example 2: 
# input : acdbdba
# output: 1