Find the number of numbers 1 to n in decimal notation.

Meaning: for example, if the number of 1 to 10 contains 1 and 10, the total number of 1 is 2.

 

Use the following method:

First, a problem is solved: given a number, the number of 1 is obtained.

Public int getnum (int n) {int COUNT = 0; while (n! = 0) {If (N % 10 = 1) {count ++;} n = N/10;} return count ;}

Then, use a loop to find the number of all 1 in all numbers 1 to n.

 

Public int getonenumton (int n) {int Total = 0; For (INT I = 1; I <= N; I ++) {total + = This. getnum (I);} return total ;}