Problem Description
Here is a function f(x):
int f ( int x ) {
if ( x == 0 ) return 0;
return f ( x / 10 ) + x % 10;
}
Now, you want to know, in a given interval [A, B] (1 <= A <= B <= 109), how many integer x that mod f(x) equal to 0.
Input
The first line has an integer T (1 <= T <= 50), indicate the number of test cases.
Each test case has two integers A, B.
Output
For each test case, output only one line containing the case number and an integer indicated the number of x.
Sample Input
21 10
11 20
Sample Output
Case 1: 10
Case 2: 3
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记忆化搜索:
数据范围是10的9次方,数位和最大为9*9=81,枚举数位和
每次要维护:pos维数,当前数位和a,枚举的数位和b,当前的模mo,有无上限e
dp [pos] [a] [b] [mo];
#include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #include<vector> #include<queue> #include<deque> #include<stack> #include<map> #include<set> #include<cmath> #include<cstdlib> #include<cctype> #define inf 0x3f3f3f3f #define maxn 10000 typedef long long LL; using namespace std; int dp[11][82][82][82]; int num[11],pos,n,m; int dfs(int pos,int a,int b,int mo,int e) { if(pos==-1) return a==b&&!mo; if(!e&&dp[pos][a][b][mo]!=-1) return dp[pos][a][b][mo]; int end=e?num[pos]:9; int sum=0; for(int i=0;i<=end;i++){ sum+=dfs(pos-1,a+i,b,(mo*10+i)%b,e&&i==end); } return e?sum:dp[pos][a][b][mo]=sum; } void Init(int x) { pos=0; while(x){ num[pos++]=x%10; x/=10; } } int cal(int x) { Init(x); int res=0; for(int i=1;i<=81;i++){ res+=dfs(pos-1,0,i,0,1); } return res; } int main() { int t,iCase=1; memset(dp,-1,sizeof dp); cin>>t; while(t--){ scanf("%d%d",&m,&n); printf("Case %d: %d\n",iCase++,cal(n)-cal(m-1)); } return 0; }