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36 lines
716 B
Ruby
36 lines
716 B
Ruby
# Find majority element(if exists) in a given array.
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# A majority element in an array A[] of size n is an element that appears more than n/2 times
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#Time-complexity: O(n), Auxiliary-space:O(1)
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#Moore's Voting algorithm
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def majority_element(a)
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len=a.length
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maj_index=0
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count=1
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for i in 1...len
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if a[i]==a[maj_index]
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count+=1
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else
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count-=1
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end
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if count==0
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a[maj_index]=a[i]
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count=1
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end
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end
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candidate=a[maj_index]
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count=0
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for i in 0...len
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if a[i]==candidate
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count+=1
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end
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end
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if count > (len/2)
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return candidate
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else
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return -1
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end
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end
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majority_element([2, 2, 3, 5, 2, 3]) |