Counting-Sort

LeetCode 1833 note: buy the cheapest first; the problem asks for counting sort, and with values up to 10^5 each price buys min(count, coins // price)

LeetCode 1122 note: count first, emit values in arr2’s order, then append the remaining values in ascending order

LeetCode 1051 note: sort and count the positions that differ from the original

LeetCode 561 note: sort and pair neighbors; each pair’s minimum is the element at an even index, so sum those