1 #let‘s begin, generate a sample with 5 kinds of animals
  2 begin=sample(1:5,100,replace = TRUE)
  3 
  4 #generate n random numbers come from 5 categories
  5 r=function(n){
  6   r=sample(1:5,n,replace = TRUE)
  7 }
  8 
  9 #define play styles
 10 play.row=function(data){
 11   #count how many times been eliminated
 12   count.row=0
 13   for (i in 1:nrow(data)){
 14     for (j in 1:(ncol(data)-2)){
 15       while (data[i,j]==data[i,j+1] & data[i,j+1]==data[i,j+2]) {
 16         count.row=count.row+1
 17         if (j==1) {
 18           data[i,1:(j+2)]=c(r(3))
 19         }
 20         else if (j>1) {
 21           data[i,1:(j+2)]=c(r(3),data[i,1:(j-1)])
 22         }
 23       }
 24     }
 25   }
 26   return (list(data,count.row))
 27 }
 28 
 29 play.col=function(data){
 30   #count how many times been eliminated
 31   count.col=0
 32   for (j in 1:ncol(data)){
 33     for (i in 1:(nrow(data)-2)){
 34       while (data[i,j]==data[i+1,j] & data[i+1,j]==data[i+2,j]){
 35         count.col=count.col+1
 36         if (i==1){
 37           data[1:(i+2),j]=c(r(3))
 38         }
 39         else if (i>1){
 40           data[1:(i+2),j]=c(r(3),data[1:(i-1),j])
 41         }
 42       }
 43     }
 44   }
 45   return (list(data,count.col))
 46 }
 47 
 48 #make a move
 49 move=function(data,i,j,k){
 50   if( (i <=nrow(data)) &
 51          (j <=ncol(data)) ){
 52     if (k=="row"){
 53       tmp=data[i,j]
 54       data[i,j]=data[i,j+1]
 55       data[i,j+1]=tmp
 56     }
 57     else if (k=="col"){
 58       tmp=data[i,j]
 59       data[i,j]=data[i+1,j]
 60       data[i+1,j]=tmp
 61     }
 62     else print("Error in move!")
 63     
 64   }
 65   if ((i >nrow(data)) |
 66       (j >ncol(data)) ){
 67     print ("Out of Bound Error !")
 68   }
 69   return(data)
 70 }
 71 
 72 #choose the best move
 73 best.move=function(data){
 74   choice=matrix(nrow=nrow(data)-1,ncol=ncol(data)-1)
 75   for (i in 1:(nrow(data)-1)){
 76     for (j in 1:(ncol(data)-1)){
 77       for (k in c("row","col")) {
 78         choice[i,j]=as.numeric(play.col(move(data,i,j,k))[2])+as.numeric(play.row(move(data,i,j,k))[2])
 79       }
 80     }
 81   }
 82   print(choice)
 83 }
 84 
 85 
 86 #start to play
 87 origin=matrix(ncol=10,nrow=10,data=http://www.mamicode.com/begin)
 88 #eliminate with original style
 89 clean=data.frame(play.col(data.frame(play.row(origin)[1]))[1])
 90 #try to make a best move
 91 best.move(clean)
 92 #in this case, we can find the best move is row=4 and col=5. but it depends on the random numbers when eliminating them.
 93 #so we can take this as a reference.
 94 new=move(clean,4,5,"row")
 95 #eliminate numbers again...
 96 new.origin=data.frame(play.col(data.frame(play.row(new)[1]))[1])
 97 #and then play again...
 98 
 99 #BTW, if there is no way to eliminate any numbers in making one step, just reorder the matrix..
100 if ((play.col(new.origin)[2]==0) & 
101     (play.row(new.origin)[2]==0)) {
102   tmp=c()
103   for (p in (1:nrow(new.origin))){
104     for (q in (1:ncol(new.origin))){
105       tmp=c(tmp,new.origin[p,q])
106     }
107   }
108   reorder.origin=matrix(ncol=10,nrow=10,data=http://www.mamicode.com/tmp)
109 }
110 
111 #afterall, it can not be stopped..