int NumberOf1Between1AndN_Solution(int n ) { // write code here if(n==0) return 0; int sum=0; for(int i=1;i<=n;i++){ int j,t=i; while(1) { if(j==1) sum++; j=t%10; t=t/10; if(t==0&&j==0) break; } } return sum; }