[R] Please correct my iterative merge sort code. The lack of recursion in the code is the main condition.

[Александр Дубровский]

mrg <- function(A,B){
  R <- c()
  while(length(A)>0  length(B)>0){
    if(A[1]<B[1]){
      R <- c(R,A[1])
      A <- A[-1]
    } else{
      R <- c(R,B[1])
      B <- B[-1]
    }
  }
  return(c(R,A,B))
}
msort <- function(A){
  if(length(A)<2){
    return(A)
  } else{
    R <- c()
    W <- c()
    x <- 8
      for(i in 1:length(A)){
        if(i%%2==0){
      R <- c(R,mrg(A[(i-1)],A[i]))
        }
      }
     }
  if((length(A)%%2)==1){
    R <- c(R,A[length(A)])
  }
  for(i in 1:length(R)){
    if(i%%4==0){
      j <- i
      W <- c(W,mrg(R[(j-3):(j-2)],R[(j-1):j]))
    }
  }
  if((length(R)%%4)==3){
    W <- c(W,mrg(R[(j+1):(j+2)],R[(j+3)]))
  }
  if((length(R)%%4)<3 && (length(R)%%4)!=0){
    W <- c(W,R[(j+1):length(R)])
  }
  R <- W
  W <- c()
  while(x<length(R)){
    for(i in 1:length(R)){
      if(i%%x==0){
        j <- i
        W <- c(W,mrg(R[(j-(x-1)):(j-(x%/%2))],R[(j-(x%/%2)+1):j]))
      }
    }
    if((length(R)%%x)>(x%/%2)){
      W <- c(W,mrg(R[(j+1):(j+(x%/%2))],R[(j+(x%/%2)+1):length(R)]))
    }
    if((length(R)%%x)<=(x%/%2) && (length(R)%%x)!=0){
      W <- c(W,R[(j+1):length(R)])
    }
    x <- x*2
    R <- W
    W <- c()
  }
    R <- mrg(R[1:j],R[(j+1):length(R)])
  return(R)
}

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