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You are given a number n, Return the count of total numbers from 1 to n containing 4 as a digit.
Examples:
Input: n = 9
Output: 1
Explanation: 4 is the only number between 1 to 9 which contains 4 as a digit.
Input: n = 44
Output: 9
Explanation: 4, 14, 24, 34, 40, 41, 42, 43 & 44, there are total 9 numbers containing 4 as a digit.
Expected Time Complexity: O(nlogn)
Expected Auxiliary Space: O(1)
Constraints:
1 <= n <= 105
class Solution {
public static int countNumberswith4(int n) {
int count=0;
for(int i=1; i<=n; i++){
if(isContainsNumFour(i)) count++;
}
return count;
}
public static boolean isContainsNumFour(int num){
while (num > 0 ){
if(num%10==4) return true;
num=num/10;
}
return false;
}
}
/*
Count numbers containing 4
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You are given a number n, Return the count of total numbers from 1 to n containing 4 as a digit.
Examples:
Input: n = 9
Output: 1
Explanation: 4 is the only number between 1 to 9 which contains 4 as a digit.
Input: n = 44
Output: 9
Explanation: 4, 14, 24, 34, 40, 41, 42, 43 & 44, there are total 9 numbers containing 4 as a digit.
Expected Time Complexity: O(nlogn)
Expected Auxiliary Space: O(1)
Constraints:
1 <= n <= 105
*/
