【CF1017B】The Bits（模拟）

题意：给定两个二进制数字a,b，可以任意交换a中的两个bit位，求进行这样一次操作，最多可产生多少种不同的a or b

n<=1e5

思路：模拟，分类讨论

 #include<cstdio>
 #include<cstring>
 #include<string>
 #include<cmath>
 #include<iostream>
 #include<algorithm>
 #include<map>
 #include<set>
 #include<queue>
 #include<vector>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef pair<int,int> PII;
 typedef vector<int> VI;
 #define fi first
 #define se second
 #define MP make_pair
 #define N   110000
 #define MOD 1000000007
 #define eps 1e-8
 #define pi acos(-1)

 char a[N],b[N];

 int read()
 {
    int v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();
    return v*f;
 }

 void swap(int &x,int &y)
 {
     int t=x;x=y;y=t;
 }

 int main()
 {
     //freopen("1.in","r",stdin);
     //freopen("1.out","w",stdout);
     int n;
     scanf("%d",&n);
     scanf("%s",a);
     scanf("%s",b);
     //printf("%s\n",a);
     //printf("%s\n",b);
     ll ans=;
     ll x=;
     ll y=;
     ll z=;
     ll w=;
     for(int i=;i<=n-;i++)
     {
          if(a[i]==''&&b[i]=='') x++;
          if(a[i]==''&&b[i]=='') y++;
          if(a[i]==''&&b[i]=='') z++;
          if(a[i]==''&&b[i]=='') w++;
     }
     ans=x*y+x*w+z*y;
     printf("%lld\n",ans);
     return ;
 }