hdoj 3555 Bomb

题目链接：Bomb

题目大意：给你一个N，问小于等于这个N的数里面“要49”的数有多少个

题目思路：跟不要62类似，数位dp去做就好了

#include <map>#include <set>#include <queue>#include <stack>#include <cmath>#include <vector>#include <cstdio>#include <cstring>#include <cstdlib>#include <iostream>#include <algorithm>using namespace std;typedef long long ll;ll a[1005],dp[1005][2],n;ll dfs(ll pos,ll pre,ll sta,bool limit){    if(pos == -1) return 1;    if(!limit&&dp[pos][sta] != -1) return dp[pos][sta];    ll up = limit?a[pos]:9;    ll tmp = 0;    for(ll i = 0;i <= up;i++){        if(pre == 4&&i == 9) continue;        tmp += dfs(pos-1,i,i == 4,limit&&i == a[pos]);    }    if(!limit) dp[pos][sta] = tmp;    return tmp;}ll solve(ll x){    ll pos = 0;    while(x){        a[pos++] = x%10;        x/=10;    }    return dfs(pos-1,-1,0,true);}int main(){    ll t,n;    memset(dp,-1,sizeof(dp));    scanf("%lld",&t);    while(t--){        scanf("%lld",&n);        printf("%lld\n",n-solve(n)+solve(0));    }    return 0;}