Poj Solution 3670

http://poj.org/problem?id=3670

/* @author: */
import java.util.Scanner;
import java.util.Arrays;
public class Main{
  static int mintwo(int a,int b){ return a< b?a:b; }
  static int minthird(int a,int b,int c){
    int temp=mintwo(a,b);
    return mintwo(temp,c);   
} 

 public static void main(String args[]){
   Scanner sc=new Scanner(System.in);
 
   int f[][]=new int[30010][3];
   int g[][]=new int[30010][3];
   int v[]=new int[30010];
   int n=sc.nextInt();
    
  for(int i=1;i<=n;i++){
   v[i]=sc.nextInt();  
   f[i][0]=f[i-1][0];
   if(v[i]!=1) f[i][0]++;
   f[i][1]=mintwo(f[i-1][0],f[i-1][1]);
   if(v[i]!=2) f[i][1]++;
   f[i][2]=minthird(f[i-1][0],f[i-1][1],f[i-1][2]);
   if(v[i]!=3) f[i][2]++;                 
  }
     for(int i=1;i<=n;i++){
        g[i][2]=g[i-1][2];
        if(v[i]!=3) g[i][2]++;
        g[i][1]=mintwo(g[i-1][2],g[i-1][1]);
        if(v[i]!=2) g[i][1]++;
        g[i][0]=minthird(g[i-1][2],g[i-1][1],g[i-1][0]);
        if(v[i]!=1) g[i][0]++;        
     }
     int mins=100000000;
     for(int i=0;i< 3;i++){
          if(mins>f[n][i]) mins=f[n][i];
          if(mins>g[n][i]) mins=g[n][i];       
     }
     System.out.printf("%dn",mins);
   }
}