Luogu P2657 [SCOI2009]windy数——数位dp

#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
using namespace std;

int a,b,shu[15],dp[15][10][2];

inline int windy(int len,int last,bool limit,bool have){
	if(len==0)return 1;
	if(!limit&&dp[len][last][have])return dp[len][last][have];
	int maxi=limit?shu[len]:9,ans=0;
	for(int i=0;i<=maxi;i++){
		if(have&&abs(i-last)<2)continue;
		ans+=windy(len-1,i,limit&&i==maxi,have||i);
	}
	if(!limit)dp[len][last][have]=ans;
	return ans;
}

inline int solve(int x){
	memset(shu,0,sizeof(shu));
	int tot=0;
	while(x){
		shu[++tot]=x%10;
		x/=10;
	}
	return windy(tot,0,true,false);
}

int main(){
	scanf("%d%d",&a,&b);
	printf("%d
",solve(b)-solve(a-1));
}

注意有绝对值