Answer to Question #292619 in Python for Dhanaraju

Question

Swap Letters

Anil is given a sentense S.He tries to make this sentence special.A sentence can be made special by swapping the character with the highest frequency with the character having the lowest frequency in the sentence.Help Anil by transforming the sentence into a special Sentence.

Note:

Consider Upper and lower case letters as different.

If there are multiple letters with the same frequency, choose the lower case letter that comes earliest in dictionary order.

a.If letters like x and B have the same frequency consider x.

b.If letters like x and b have the same frequency consider b.

Input

The first line of input is a string.

sample input1

Python is a programming language.

sample output1

Python is e progremming lenguega.

sample input2

CHECK your blood PRESSURE frequently.

sample output2

CHECK ybur olbbd PRESSURE frequently.

Answer 1

def selectLetter(ch1, ch2):
    if 'a' <= ch1 <= 'z' and 'A' <= ch2 <= 'Z':
        return ch1
    if 'a' <= ch2 <= 'z' and 'A' <= ch1 <= 'Z':
        return ch2
    if ch1 < ch2:
        return ch1
    return ch2


def specialSentence(s):
    D = {}
    for ch in s:
        if 'a' <= ch <= 'z' or 'A' <= ch <= 'Z':
            D[ch] = D.get(ch, 0) + 1
    
    minFr = len(s)+1
    lessFrCh = None
    maxFr = 0
    moreFrCh = None
    for ch in D:
        if D[ch] < minFr:
            minFr = D[ch]
            lessFrCh = ch
        elif D[ch] == minFr:
            lessFrCh = selectLetter(ch, lessFrCh)
        
        if D[ch] > maxFr:
            maxFr = D[ch]
            moreFrCh = ch
        elif D[ch] == maxFr:
            moreFrCh = selectLetter(ch, moreFrCh)
    
    res = ''
    for ch in s:
        if ch == lessFrCh:
            res += moreFrCh
        elif ch == moreFrCh:
            res += lessFrCh
        else:
            res += ch

    return res


def main():
    s = input()
    ss = specialSentence(s)
    print(ss)


main()