M × N Puzzle

http://poj.org/problem?id=2893

来自逆序对的强大力量

 #include<iostream>
 #include<stdio.h>
 #include<algorithm>
 #include<cstring>
 #define lowbit(x)(x&-x)
 using namespace std;
 int c[],a[][],maxn,n,m,d[];
 void update(int k,int x){for(int i=k;i<=maxn;i+=lowbit(i))c[i]+=x;}
 int getsum(int x)
 {
     int ans=;
     for(int i=x;i;i-=lowbit(i))ans+=c[i];
     return ans;
 }
 int main()
 {
     while()
     {

         int cnt=,num=;
         scanf("%d%d",&m,&n);
         if(m==&&n==) break;
         maxn=m*n;
         for(register int i=;i<=maxn;++i)
         {
             c[i]=d[i]=;
         }
         int kl;
         for(int i=;i<=m;++i)
          for(int j=;j<=n;++j)
          {
              scanf("%d",&a[i][j]);
              if(a[i][j]==){kl=i;continue; }
              d[++cnt]=a[i][j];
              update(d[cnt],);
              num+=cnt-getsum(d[cnt]);
          }
         if(n%==)
         {
             if(num%==)printf("YES\n");
             else printf("NO\n");
         }
         else
         {
             if((m-kl+num)%==)printf("YES\n");
             else printf("NO\n");
         }
     }
 }