_645. Set Mismatch.md

645. Set Mismatch

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First completed : June 01, 2024

Last updated : July 19, 2024

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Related Topics : Array, Hash Table, Bit Manipulation, Sorting

Acceptance Rate : 44.59 %

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Solutions

• e645 v1 moderate runtime.java
• e645 v2 even slower.java
• e645.py

Java

e645 v1 moderate runtime.java

// Not that good of a runtime

class Solution {
    public int[] findErrorNums(int[] nums) {
        int intendedSum = ((1 + nums.length) * nums.length) / 2;
        int actualSum = 0;

        HashSet<Integer> seenSet = new HashSet<>();
        int repeat = -1;
        
        for (int i: nums) {
            actualSum += i;
            
            if (seenSet.contains(i)) {
                repeat = i;
            }
            seenSet.add(i);
        }

        return new int[]{repeat, (repeat + intendedSum - actualSum)};
    }
}

e645 v2 even slower.java

// Consistently 5% percentile --> bad runtime but works

class Solution {
    public int[] findErrorNums(int[] nums) {
        byte[] corrects = new byte[nums.length];

        int dupe = -1;
        for (int i = 0; i < nums.length; i++) {
            corrects[nums[i] - 1] += 1;

            if (corrects[nums[i] - 1] == 2) {
                dupe = nums[i];
            }
        }

        for (int i = 0; i < corrects.length; i++) {
            System.out.println(corrects[i]);
        }

        int index = 0;
        while (true) {
            if (corrects[index] == 0) {
                return new int[]{dupe, index + 1};
            }
            index++;
        }

    }
}

Python

e645.py

class Solution:
    def findErrorNums(self, nums: List[int]) -> List[int]:
        correctSum = ((1 + len(nums)) * len(nums)) // 2
        currentSum = sum(nums)
        dupeVal = -1
        pastVals = set()

        for i in range(0, len(nums)) :
            if nums[i] in pastVals :
                dupeVal = nums[i]
                break
            pastVals.add(nums[i])

        print(dupeVal, correctSum, currentSum)
        missingVal = dupeVal + correctSum - currentSum

        return [dupeVal, missingVal]