Find pair with sum Ruby Algorithm
Jan 17, 2021
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Given an array A[] and a number x, check for pair in A[] with sum as x
— Approach 1: Using Hash Map
def check_pair(arr,x)
len=arr.length
flag=false
map=Hash.new()
for i in 0…len
t=x-arr[i]
if map[t]
flag=true
break
end
map[arr[i]]=1
end
if flag
return “Array has two elements with sum:#{x}”
else
return “Array doesn’t have two elements with sum:#{x}”
end
end
check_pair([5,4,10,-2,3,2,-1,9],9)
— Approach 2: Sorting and then searching using left and right indexes.
def check_pair(arr,x)
len=arr.length
arr.sort!
left=0
right=len-1
while left<right
if (arr[left]+arr[right]==x)
return “Array has two elements with sum:#{x}”
elsif (arr[left]+arr[right]>x)
right-=1
else
left+=1
end
end
return “Array doesn’t have two elements with sum:#{x}”
end
check_pair([5,4,10,-2,3,2,-1,9],9)
