LeetCode

LeetCode 728 note: check every number in the range; each digit must be nonzero and divide the number

LeetCode 709 note: an uppercase letter plus 32 in ASCII is its lowercase form; other characters stay

LeetCode 705 note: a fixed number of buckets, with the key modulo the bucket count choosing the bucket and a list per bucket handling collisions

LeetCode 704 note: a closed interval [l, r] with an integer mid; return on a match, otherwise discard the half that cannot contain the target

LeetCode 703 note: keep a min-heap of size k; its top is the k-th largest

LeetCode 700 note: go left when the node is larger, right when smaller, and return the node when found

LeetCode 697 note: record each value’s count, first index and last index; among the most frequent values, take the shortest span

LeetCode 696 note: split the string into runs of equal characters; each adjacent pair of runs contributes min(previous, current) substrings

LeetCode 693 note: alternating bits means the binary string has neither 00 nor 11; in bits, n ^ (n » 1) is all ones

LeetCode 682 note: keep valid scores on a stack; C removes the last, D adds its double, and + adds the sum of the last two

LeetCode 680 note: at the first mismatch the only options are deleting the left or the right character; check whether either remainder is a palindrome

LeetCode 674 note: one pass that extends the run while strictly increasing and resets to 1 otherwise, updating the maximum after the loop too