/**
* Finds the element with the minimum occurrences in an array.
*
* @template T
* @param {T[]} array - The input array to process.
* @returns {T | null} The element with the lowest frequency, or null if empty.
*/
function findMinOccurrence(array) {
if (!Array.isArray(array) || array.length === 0) {
return null;
}
// 1. Tally element frequencies using a Map (handles any type, including primitives and objects)
const counts = array.reduce((acc, item) => {
acc.set(item, (acc.get(item) || 0) + 1);
return acc;
}, new Map());
// 2. Find the entry with the minimum count in O(K) time
let minElement = null;
let minCount = Infinity;
for (const [item, count] of counts.entries()) {
if (count < minCount) {
minCount = count;
minElement = item;
}
}
return minElement;
}
// Example usage:
const arr = [1, 3, 1, 1, 4, 4, 5, 5, 4, 2, 2, 2, 3, 3, 3];
const result = findMinOccurrence(arr);
if (result !== null) {
console.log(result); // Output: 5
} else {
console.log("The array was empty or invalid.");
}
/*
run:
5
*/
