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
1 #include<cstdio> 2 #include<cstring> 3 #include<string> 4 #include<cmath> 5 #include<iostream> 6 #include<algorithm> 7 #include<map> 8 #include<set> 9 #include<queue> 10 #include<vector> 11 using namespace std; 12 typedef long long ll; 13 typedef unsigned int uint; 14 typedef unsigned long long ull; 15 typedef pair<int,int> PII; 16 typedef vector<int> VI; 17 #define fi first 18 #define se second 19 #define MP make_pair 20 #define N 110000 21 #define MOD 1000000007 22 #define eps 1e-8 23 #define pi acos(-1) 24 25 char a[N],b[N]; 26 27 int read() 28 { 29 int v=0,f=1; 30 char c=getchar(); 31 while(c<48||57<c) {if(c=='-') f=-1; c=getchar();} 32 while(48<=c&&c<=57) v=(v<<3)+v+v+c-48,c=getchar(); 33 return v*f; 34 } 35 36 void swap(int &x,int &y) 37 { 38 int t=x;x=y;y=t; 39 } 40 41 42 int main() 43 { 44 //freopen("1.in","r",stdin); 45 //freopen("1.out","w",stdout); 46 int n; 47 scanf("%d",&n); 48 scanf("%s",a); 49 scanf("%s",b); 50 //printf("%s ",a); 51 //printf("%s ",b); 52 ll ans=0; 53 ll x=0; 54 ll y=0; 55 ll z=0; 56 ll w=0; 57 for(int i=0;i<=n-1;i++) 58 { 59 if(a[i]=='0'&&b[i]=='0') x++; 60 if(a[i]=='1'&&b[i]=='0') y++; 61 if(a[i]=='0'&&b[i]=='1') z++; 62 if(a[i]=='1'&&b[i]=='1') w++; 63 } 64 ans=x*y+x*w+z*y; 65 printf("%lld ",ans); 66 return 0; 67 }