CODE FESTIVAL 2017 qual A C Palindromic Matrix（思维题）

 1 //Atcoder 3
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 using namespace std;
 6  
 7 int num[30];
 8  
 9 int main(){
10     memset(num,0,sizeof(num));
11     char tmp;
12     int n,m;
13     cin>>n>>m;
14     for(int i=1;i<=n;i++)
15     for(int j=1;j<=m;j++)
16     cin>>tmp,num[tmp-‘a‘]++;
17     
18     if(n%2==0&&m%2==0){//偶偶 
19         int cnt4=0;
20         for(int i=0;i<26;i++){
21             cnt4+=num[i]/4;num[i]%=4;
22         }
23         if(4*cnt4!=n*m) {cout<<"No"<<endl;return 0;}
24     }
25     else if((n*m)%2==1){//奇奇 
26         int cnt1=0,cnt2=0,cnt4=0;
27         for(int i=0;i<26;i++){
28             cnt4+=num[i]/4;num[i]%=4;
29             cnt2+=num[i]/2;num[i]%=2;
30             cnt1+=num[i];
31         }
32         if(cnt1!=1||(2*cnt2+4*cnt4)!=(n*m-1)||(4*cnt4)<(n*m-1-2*(n/2+m/2))) 
33         {cout<<"No"<<endl;return 0;}
34     }
35     else if((n*m)%2==0){//奇偶
36         int cnt2=0,cnt4=0; 
37         for(int i=0;i<26;i++){
38             cnt4+=num[i]/4;num[i]%=4;
39             cnt2+=num[i]/2;num[i]%=2;
40         }
41         if((2*cnt2+4*cnt4)!=(n*m)||(4*cnt4<(m/2*2)*(n/2*2)))
42         {cout<<"No"<<endl;return 0;}
43     }
44     
45     cout<<"Yes"<<endl;
46     return 0;
47 }