【DP】 HDOJ 3555 Bomb

一道不错的数位DP。。。

#include <iostream> 
#include <queue> 
#include <stack> 
#include <map> 
#include <set> 
#include <bitset> 
#include <cstdio> 
#include <algorithm> 
#include <cstring> 
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 105
#define maxm 300006
#define eps 1e-10
#define mod 1315423911
#define INF 1e17
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid 
#define rson o<<1 | 1, mid+1, R 
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head

LL dp[maxn][10][2];
int num[maxn];
int n;

void read(void)
{
	LL t;
	scanf("%I64d", &t);
	n = 0;
	while(t) num[++n] = t%10, t /= 10;
	num[0] = 0;
}

LL dfs(int pos, int pre, int istrue, int limit)
{
	if(pos <= 0) return istrue;
	if(!limit && dp[pos][pre][istrue] != -1) return dp[pos][pre][istrue];
	int b = limit == 1 ? num[pos] : 9;
	LL ans = 0;
	for(int i = 0; i <= b; i++) ans += dfs(pos-1, i, istrue || (pre == 4 && i == 9), limit && (i == b));
	//printf("pos = %d pre = %d istrue = %d ans = %d\n", pos, pre, istrue, ans);
	if(!limit) dp[pos][pre][istrue] = ans;
	return ans;
}

void work(void)
{
	//memset(dp, -1, sizeof dp);
	LL ans = 0;
	ans = dfs(n, 0, 0, 1);
	printf("%I64d\n", ans);
}


int main(void)
{
	int _;
	while(scanf("%d", &_)!=EOF) {
		while(_--) {
			read();
			work();
		}
	}
	return 0;
}