【题解】牛客 Numbers⭐⭐ 【Dfs】

牛客 Numbers

Input

Output

For each test case, print an integer which denotes the result.

Examples

输入
复制
999
233333
0123456789
输出
复制
2
0
55

题意:

给出一个数, 问1-99有几种方案组成他

题解:

数位简单Dfs

#include
using namespace std;
#define ms(x, n) memset(x,n,sizeof(x));
typedef  long long LL;
const int INF = 1 << 30;
const int MAXN = 110;

string s;
int len, ans = 0;
bool used[MAXN];
void Dfs(int p){
    if(p == len){
        ++ans;
        return;
    }
    if(!used[stoi(s.substr(p, 1))]){
        used[stoi(s.substr(p, 1))] = true;
        Dfs(p+1);
        used[stoi(s.substr(p, 1))] = false;
    }
    if(p+2 <= len && s[p] != '0' && !used[stoi(s.substr(p, 2))]){
        used[stoi(s.substr(p, 2))] = true;
        Dfs(p+2);
        used[stoi(s.substr(p, 2))] = false;
    }
}
int main() {
    ios::sync_with_stdio(false);
    while(cin >> s){
        ms(used, 0);
        len = s.length(), ans = 0;
        Dfs(0);
        cout << ans << endl;
    }
    return 0;
}