Codeforces Round #742 (Div. 2) C. Carrying Conundrum

传送门

题意:

给你一个数n,并规定了一种特殊的运算规则,问你有多少种选择使得a,b在该运算规则下相加等于n。

思路:

因为进位不再是向左1位进,而是向左2位进位,因而可以把奇偶位分开来看,将奇数位的数组成一个数字,并得出组成该数字的方法数,偶数位同理,两者相乘-2即为答案(a,b不全为0).

#include<bits/stdc++.h>
#include<ctime>
using namespace std;
#define ll long long 
ll a[100];
ll sum[110];
ll res[110];

int main()
{
    
    
	int t;
	cin>>t;
	while(t--)
	{
    
    
		memset(sum, 0, sizeof(sum));
		ll n;
		cin>>n;
		ll ans = 1;
		int cnt = 0;
		while(n)
		{
    
    
			a[++cnt] = n%10;
			n/=10;
		}
		int flag = 0;
		for(int i = 1; i <= cnt/2; i++)
		{
    
    
			int op = a[i];
			a[i] = a[cnt-i+1];
			a[cnt-i+1] = op;
		}
		ll now = 0;
		for(int i = 1; i <= cnt; i += 2)
		{
    
    
			now = now*10+a[i];
		}
		ans = now+1;
		now = 0;
		for(int i = 2; i <= cnt; i += 2)
		{
    
    
			now = now*10+a[i];
		}
		ll ans2 = now+1;
		cout<<ans*ans2 - 2<<endl;
	}
}

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Origin blog.csdn.net/p15008340649/article/details/120156363
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