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题目:数字游戏
思路:数位dp
代码:
#include<bits/stdc++.h>
using namespace std;
int a,b,n;
int c[20];
int dp[20][200];
int dfs(int len,int sum,int limit) {
if(len==0&&sum==0) return true;
else if(len==0) return false;
if(!limit&&(~dp[len][sum])) return dp[len][sum];
int up=9;
if(limit) up=c[len];
int ans=0;
for(int i=0;i<=up;i++) {
ans+=dfs(len-1,(sum+i)%n,limit&&(i==c[len]));
}
if(!limit) dp[len][sum]=ans;
return ans;
}
int slv(int x){
memset(dp,-1,sizeof(dp));
int len=0;
while(x) {
c[++len]=x%10;
x/=10;
}
return dfs(len,0,true);
}
int main() {
while(~scanf("%d%d%d",&a,&b,&n))
printf("%d\n",slv(b)-slv(a-1));
return 0;
}