leetcode NumberOfDigitOne
z
 2019-04-09 10:36:27   
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public class NumberOfDigitOne {
  /**
   * Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.
   *
   * Example:
   *
   * Input: 13
   * Output: 6
   * Explanation: Digit 1 occurred in the following numbers: 1, 10, 11, 12, 13.
   *
   */
  public static int countDigitOne(int n) {
    int count = 0;
    for (int i = 0; i<=n; i=i*10){
      int p = n/i;
      int q = n%i;
      count += p*10 ;
    }
    return count;
  }
  public static void main(String[] argg){
    System.out.println(countDigitOne(91));
  }
}