HDU - 3555 Bomb

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1.题面

http://acm.hdu.edu.cn/showproblem.php?pid=3555

2.题意

求在[a,b]区间中，有多少数字是含有49这个串的。

3.思路

数位dp，注意到没有限制的时候，后面所能表示的数是一样的

我一开始使用了一种奇怪的写法，不过也过了

4.代码

通过的代码

/*****************************************************************    > File Name: Cpp_Acm.cpp    > Author: Uncle_Sugar    > Mail: uncle_sugar@qq.com    > Created Time: 2016年07月27日 星期三 19时33分33秒*****************************************************************/# include <cstdio># include <cstring># include <cctype># include <cmath># include <cstdlib># include <climits># include <iostream># include <iomanip># include <set># include <map># include <vector># include <stack># include <queue># include <algorithm>using namespace std;template<class T>void PrintArray(T* first,T* last,char delim=' '){     for (;first!=last;first++) cout << *first << (first+1==last?'\n':delim); }const int debug = 1;const int size  = 10 + 30; const int INF = INT_MAX>>1;typedef long long ll;int num[size];int len;ll dp[30][20][2];ll dfs(int pos,int pre,int statue,int limit){    if (pos==-1)        return statue;    if (limit!=1&&dp[pos][pre][statue]!=-1)        return dp[pos][pre][statue];    int ub = limit?num[pos]:9;    ll ret = 0;    for (int i=0;i<=ub;i++){        ret += dfs(pos-1,i,statue||(pre==4&&i==9),limit&&i==ub);    }    if (limit==0)        dp[pos][pre][statue] = ret;    return ret;}ll solve(ll n){    len = 0;    while (n){        num[len++] = n%10;        n /= 10;    }    return dfs(len-1,-1,0,1);}int main(){    std::ios::sync_with_stdio(false);cin.tie(0);    int i,j;    int T;    cin >> T;    memset(dp,-1,sizeof(dp));    while (T--){        ll a;        cin >> a;        cout << solve(a) << endl;    }    return 0;}

奇怪的写法

/*****************************************************************    > File Name: Cpp_Acm.cpp    > Author: Uncle_Sugar    > Mail: uncle_sugar@qq.com    > Created Time: 2016年07月27日 星期三 19时33分33秒*****************************************************************/# include <cstdio># include <cstring># include <cctype># include <cmath># include <cstdlib># include <climits># include <iostream># include <iomanip># include <set># include <map># include <vector># include <stack># include <queue># include <algorithm>using namespace std;template<class T>void PrintArray(T* first,T* last,char delim=' '){     for (;first!=last;first++) cout << *first << (first+1==last?'\n':delim); }const int debug = 1;const int size  = 10 + 30; const int INF = INT_MAX>>1;typedef long long ll;int num[size];int len;ll dp[30][20][2][2];ll dfs(int pos,int pre,int statue,int limit){    if (pos==-1)        return statue;    if (dp[pos][pre][statue][limit]!=-1)        return dp[pos][pre][statue][limit];    int ub = limit?num[pos]:9;    ll ret = 0;    for (int i=0;i<=ub;i++){        ret += dfs(pos-1,i,statue||(pre==4&&i==9),limit&&i==ub);    }    if (dp[pos][pre][statue][limit]==-1)        dp[pos][pre][statue][limit] = ret;    return ret;}ll solve(ll n){    memset(dp,-1,sizeof(dp));    len = 0;    while (n){        num[len++] = n%10;        n /= 10;    }    return dfs(len-1,0,0,1);}int main(){    std::ios::sync_with_stdio(false);cin.tie(0);    int i,j;    int T;    cin >> T;    while (T--){        ll a;        cin >> a;        cout << solve(a) << endl;    }    return 0;}

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