70 lines
1.7 KiB
Ruby
70 lines
1.7 KiB
Ruby
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#Given an unsorted array,find the minimum length of subarraay,sorting which sorts the whole array.
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#Time-complexity: O(n),Auxiliary-space:O(1)
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=begin
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Algorithm: Scan left to right and find first index where next element is less than current,let it be l
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(if l==a.length-1 it is already sorted),similarly scan right to left and search first index
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where previous element is larger than current,let it be r.Now search for min and max in l to r,
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now from 0 to l-1 find first element which is greater than min(let it be i) and
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from r+1 to a.length-1 find first element which is less than max.(let it be j)
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set l= i and r=j
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minimum length= r-l+1
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start=l
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end=r
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=end
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def unsorted_sub(a)
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n=a.length
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l=0
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r=n-1
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for i in 0...n-1
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if a[i]>a[i+1]
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l=i
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break
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else
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l+=1
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end
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end
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return "The complete array is sorted" if l==n-1
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for i in (n-1).downto(1)
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if a[i]<a[i-1]
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r=i
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break
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else
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r-=1
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end
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end
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min_i,max_i=find_minmax(a,l,r)
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for i in 0...l
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if a[i]>a[min_i]
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l=i
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break
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end
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end
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for i in (n-1).downto(r+1)
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if a[i]<a[max_i]
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r=i
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break
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end
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end
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return "Length: #{r-l+1}, Starting index: #{l}, Ending index: #{r}"
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end
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def find_minmax(a,lo,hi)
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min=max=lo
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for i in (lo+1)..hi
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if a[i]>a[max]
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max=i
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elsif a[i]<min
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min=i
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else
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next
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end
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end
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return min,max
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end
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unsorted_sub([15, 16, 21, 30, 25, 41, 28, 39, 58]) # => Length: 5, Starting index: 3, Ending index: 7
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unsorted_sub([1,2,3,4,5,6]) # => The complete array is sorted
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