Alphabetical Character Frequency

The first line of input contains a single string s.

For each unique character (excluding spaces) found in the string, print a new line in the format: char: count

The lines must be sorted alphabetically by the character.

Alphabetical order refers to the standard character sort order (also known as ASCIIbetical order), where uppercase letters come before lowercase letters, and numbers/symbols have their own standard positions.

Sample Input 1:

Hello World

Sample Output 1:

H: 1
W: 1
d: 1
e: 1
l: 3
o: 2
r: 1

Explanation for Sample 1:

After ignoring the space, the characters are H, e, l, l, o, W, o, r, l, d.
The frequencies are: H(1), e(1), l(3), o(2), W(1), r(1), d(1).
Printed in alphabetical (ASCII) order, this gives the specified output.

Sample Input 2:

Programming is fun

Sample Output 2:

P: 1
a: 1
f: 1
g: 2
i: 2
m: 2
n: 2
o: 1
r: 2
s: 1
u: 1

Explanation for Sample 2:

The character 'r' appears twice, 'g' appears twice, 'm' appears twice, 'i' appears twice, and 'n' appears twice. All other characters appear once. The output is sorted by the character.

Expected Time Complexity:

The expected time complexity is O(N log K), where N is the length of the string and K is the number of unique characters.

Constraints:

0 <= length of s <= 10^5
The string consists of standard ASCII characters.

Time limit: 1 sec