Codeforces Beta Round #16 (Div. 2 Only)

水题
 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define lson l,mid,rt<<1
 4 #define rson mid+1,r,rt<<1|1
 5 #define sqr(x) ((x)*(x))
 6 #define maxn 500005
 7 typedef long long ll;
 8 /*#ifndef ONLINE_JUDGE
 9         freopen("1.txt","r",stdin);
10 #endif */
11 
12 int n,m;
13 string str[105];
14 
15 int main(){
16     #ifndef ONLINE_JUDGE
17        // freopen("1.txt","r",stdin);
18     #endif
19     cin>>n>>m;
20     int flag=0;
21     map<int,int>mp;
22     for(int i=0;i<n;i++) cin>>str[i];
23     for(int i=1;i<n;i++){
24         if(str[i][0]==str[i-1][0]) flag=1;
25     }
26     if(!flag){
27         if(m==1){
28             cout<<"YES"<<endl;
29         }
30         else{
31             for(int k=0;k<n;k++){
32                 for(int i=1;i<m;i++){
33                     if(str[k][i]!=str[k][i-1]) flag=1;
34                 }
35             }
36             if(flag) cout<<"NO"<<endl;
37             else  cout<<"YES"<<endl;
38         }
39     }
40     else{
41         cout<<"NO"<<endl;
42     }
43 }
View Code