Smallest Missing Non-negative Integer After Operations - Count Mod Values [JS]

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Description 

Solution: Count Mod Values

Numbers will be grouped by their mod value (nums[i] % value).
Numbers in the same mod group can be transformed into any number with the same mod value.
Use a hashmap to count the occurances of numbers for each mod value.

Try to create each number from 0 to n - 1.
If there are no more occurances of numbers for the current mod value, then it is impossible to have a higher MEX.

Time Complexity: O(n)
Space Complexity: O(n)

var findSmallestInteger = function(nums, value) {
  let modCount = new Map();
  for (let num of nums) {
    let mod = ((num % value) + value) % value;
    modCount.set(mod, (modCount.get(mod) || 0) + 1);
  }
  for (let i = 0; i < nums.length; i++) {
    let modValue = i % value;
    if (modCount.has(modValue) && modCount.get(modValue) > 0) {
      modCount.set(modValue, modCount.get(modValue) - 1);
    } else {
      return i;
    }
  }
  return nums.length;
};
Location: Auckland, New Zealand

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