Let us define two functions f and g on positive integer numbers.
You need to process Q queries. In each query, you will be given three integers l, r and k. You need to print the number of integers xbetween l and r inclusive, such that g(x) = k.
The first line of the input contains an integer Q (1 ≤ Q ≤ 2 × 105) representing the number of queries.
Q lines follow, each of which contains 3 integers l, r and k (1 ≤ l ≤ r ≤ 106, 1 ≤ k ≤ 9).
For each query, print a single line containing the answer for that query.
4
22 73 9
45 64 6
47 55 7
2 62 4
1
4
0
8
4
82 94 6
56 67 4
28 59 9
39 74 4
3
1
1
5
In the first example:
- g(33) = 9 as g(33) = g(3 × 3) = g(9) = 9
- g(47) = g(48) = g(60) = g(61) = 6
- There are no such integers between 47 and 55.
- g(4) = g(14) = g(22) = g(27) = g(39) = g(40) = g(41) = g(58) = 4
题目大意:f(x)的值是x非零数位的乘积.q组询问,每次问[l,r]之间的x,有多少g(x) = k;
分析:多组询问想到预处理,每次问个数想到前缀和,那么预处理一个前缀和就好了.
#include <cstdio> #include <cmath> #include <queue> #include <cstring> #include <iostream> #include <algorithm> using namespace std; typedef long long ll; int q,a[1000010],sum[1000010][10]; int solve(int x) { if (x < 10) return x; if (a[x]) return a[x]; int res = 1; while (x) { int temp = x % 10; if (temp != 0) res *= temp; x /= 10; } return a[x] = solve(res); } int main() { scanf("%d",&q); for (int i = 1; i <= 1000000; i++) { if (i < 10) a[i] = i; else a[i] = solve(i); } for (int i = 1; i <= 1000000; i++) { for (int j = 1; j <= 9; j++) sum[i][j] += sum[i - 1][j]; sum[i][a[i]]++; } while (q--) { int l,r,k; scanf("%d%d%d",&l,&r,&k); printf("%d\n",sum[r][k] - sum[l - 1][k]); } return 0; }