areSimilar.R

# Two arrays are called similar if one can be obtained from another by swapping at most one pair of elements in one of the arrays.
# 
# Given two arrays a and b, check whether they are similar.
# 
# Example
# 
# For a = [1, 2, 3] and b = [1, 2, 3], the output should be
# areSimilar(a, b) = true.
# 
# The arrays are equal, no need to swap any elements.
# 
# For a = [1, 2, 3] and b = [2, 1, 3], the output should be
# areSimilar(a, b) = true.
# 
# We can obtain b from a by swapping 2 and 1 in b.
# 
# For a = [1, 2, 2] and b = [2, 1, 1], the output should be
# areSimilar(a, b) = false.
# 
# Any swap of any two elements either in a or in b won't make a and b equal.
# 
# Input/Output
# 
#     [execution time limit] 5 seconds (r)
# 
#     [input] array.integer a
# 
#     Array of integers.
# 
#     Guaranteed constraints:
#     3 ≤ a.length ≤ 105,
#     1 ≤ a[i] ≤ 1000.
# 
#     [input] array.integer b
# 
#     Array of integers of the same length as a.
# 
#     Guaranteed constraints:
#     b.length = a.length,
#     1 ≤ b[i] ≤ 1000.
# 
#     [output] boolean
#         true if a and b are similar, false otherwise.

a = list(1, 2, 3)
b = list(2, 1, 3)


a = list(1, 2, 2)
b = list(2, 1, 1)
areSimilar <- function(a, b) {
  a = unlist(a)
  b = unlist(b)
  
  if (sum(a == b) == length(a)) {
    return(TRUE)
  } else if (sum(a != b) != 2) {
    return(FALSE)
  } else {
    #do swap
    indicesToSwap <- which(a != b)
    c = a[indicesToSwap[1]]
    a[indicesToSwap[1]] = a[indicesToSwap[2]]
    a[indicesToSwap[2]] = c
    #check
    if (sum(a == b) == length(a)) {
      return(TRUE)
    } else {
      return(FALSE)
    }
      
    #return
  }
}