# Program to find number of subsequences with i, j and k number of x, y, z letters in Python

PythonServer Side ProgrammingProgramming

Suppose we have a string s with "x", "y" and "z"s, we have to find the number of subsequences that have i number of "x" characters, followed by j number of "y" characters and followed by k number of "z" characters where i, j, k ≥ 1.

So, if the input is like s = "xxyz", then the output will be 3, as we can make two "xyz" and one "xxyz"

To solve this, we will follow these steps:

• n := size of s

• x := 0, y := 0, z := 0

• for i in range 0 to n, do

• count := 0

• if s[i] is same as "x", then

• x := x * 2

• x := x + 1

• if s[i] is same as "y", then

• y := y * 2

• y := y + x

• if s[i] is same as "z", then

• z := z * 2

• z := z + y

• return z

## Example

Live Demo

class Solution:
def solve(self, s):
n = len(s)

x = 0
y = 0
z = 0
for i in range(n):
count = 0
if s[i] == "x":
x *= 2
x += 1
if s[i] == "y":
y *= 2
y += x
if s[i] == "z":
z *= 2
z += y

return z

ob = Solution()
print(ob.solve("xxyz"))

## Input

"xxyz"

## Output

3