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Program to Find Out the Occurrence of a Digit from a Given Range in Python
Suppose we have been provided with two positive integers n and d where d is a digit within 0 to 9. We have to determine how many times the digit d appears within the integer numbers between 1 and n.
So, if the input is like n = 45, d = 5, then the output will be 5.
These numbers have the digit 5: [5, 15, 25, 35, 45].
To solve this, we will follow these steps −
Define a function solve(). This will take n and d as inputs.
if n < 0, then
return 0
k := floor of (n /10) − 1
ans := solve(k, d) * 10 + k + 1
if d is same as 0, then
ans := ans − 1
m := floor of (n / 10) * 10
while m <= n, do
ans := ans + count of occurrences of string representation of d in string representation of m.
m := m + 1
return ans
From the main function, now call the function −
value := solve(n,d)
print(value)
Let us see the following implementation to get better understanding −
Example
class Solution: def solve(self, n, d): if n < 0: return 0 k = n // 10 − 1 ans = self.solve(k, d) * 10 + k + 1 if d == 0: ans −= 1 m = n // 10 * 10 while m <= n: ans += str(m).count(str(d)) m += 1 return ans ob = Solution() print(ob.solve(45,5))
Input
45, 5
Output
5
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