Good Numbers
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3453 Accepted Submission(s): 1090
Problem Description
If we sum up every digit of a number and the result can be exactly divided by 10, we say this number is a good number.
You are required to count the number of good numbers in the range from A to B, inclusive.
Input
The first line has a number T (T <= 10000) , indicating the number of test cases.
Each test case comes with a single line with two numbers A and B (0 <= A <= B <= 1018).
Output
For test case X, output "Case #X: " first, then output the number of good numbers in a single line.
Sample Input
2 1 10 1 20
Sample Output
Case #1: 0 Case #2: 1 Hint The answer maybe very large, we recommend you to use long long instead of int.
Source
2013 ACM/ICPC Asia Regional Online —— Warmup2
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zhuyuanchen520
题意:求A到B之间 各个位数的和sum%10==0 的数的个数。
题解:数位dp,dp[i][j]表示当前i位mod10=j的个数。
#include<cstring> #include<cstdio> #include<algorithm> #include<iostream> #include<cstdlib> #define ll long long using namespace std; int n; ll dp[20][20]; int num[20]; ll a,b; ll dfs(int i,int mod,bool e) { if(i<=0)return mod?0:1; if(!e&&dp[i][mod]!=-1)return dp[i][mod]; ll res=0; int u=e?num[i]:9; for(int d=0; d<=u; d++) { int Mod=(mod+d)%10; res+=dfs(i-1,Mod,e&&d==u); } return e?res:dp[i][mod]=res; } ll solve(ll x) { int len=1; ll k=x; while(k) { num[len++]=k%10; k/=10; } num[len]=0; return dfs(len-1,0,1); } int main() { //freopen("test.in","r",stdin); int t; memset(dp,-1,sizeof dp); cin>>t; int ca=1; while(t--) { scanf("%I64d%I64d",&a,&b); printf("Case #%d: %I64d\n",ca++,solve(b)-solve(a-1)); } return 0; }
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