48 lines
1.1 KiB
Ruby
48 lines
1.1 KiB
Ruby
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#Given an array A[] and a number x, check for pair in A[] with sum as x
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#Approach 1: Using Hash Map
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#Time-complexity: O(n), Space-complexity: O(n) {extra space required for hashmap}
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def check_pair(arr,x)
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len=arr.length
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flag=false
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map=Hash.new()
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for i in 0...len
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t=x-arr[i]
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if map[t]
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flag=true
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break
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end
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map[arr[i]]=1
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end
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if flag
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return "Array has two elements with sum:#{x}"
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else
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return "Array doesn't have two elements with sum:#{x}"
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end
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end
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check_pair([5,4,10,-2,3,2,-1,9],9)
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##Approach 2: Sorting and then searching using left and right indexes.
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#Time-complexity: O(nlogn) //O(nlogn)+O(n), Space-complexity: O(1)
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def check_pair(arr,x)
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len=arr.length
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arr.sort! # You can choose your own sorting algorithm
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left=0
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right=len-1
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while left<right
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if (arr[left]+arr[right]==x)
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return "Array has two elements with sum:#{x}"
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elsif (arr[left]+arr[right]>x)
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right-=1
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else
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left+=1
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end
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end
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return "Array doesn't have two elements with sum:#{x}"
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end
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check_pair([5,4,10,-2,3,2,-1,9],9)
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