PAT a1049题解

#include <cstdio>int main(){int n, a = 1, ans = 0;int left, now, right;scanf("%d", &n);while(n / a != 0){left = n / (a * 10);now = n / a % 10;right = n % a;if(now == 0) ans += left * a;else if(now == 1) ans += left * a + right + 1;else ans += (left + 1) * a;a *= 10;}printf("%d\n", ans);return 0;}