LeetCode

LeetCode 1002 note: count each word and intersect all Counters (minimum count per character), then expand

LeetCode 993 note: cousins share a depth but not a parent; record x’s and y’s depth and parent during DFS and compare

LeetCode 989 note: treat k as the carry, add from the last element backwards, and keep prepending digits while k remains

LeetCode 977 note: the largest squares are at the two ends, so compare the ends with two pointers and fill the result from the back

LeetCode 965 note: every value must equal the root’s; compare values while recursing, not the booleans the recursion returns

LeetCode 961 note: the other n values are distinct, so the first value seen twice is the answer

LeetCode 953 note: map letters to their alien index and compare each adjacent pair at the first differing character; with no difference, the shorter must come first

LeetCode 944 note: take each column with zip(*strs) and count the columns that are not non-decreasing

LeetCode 942 note: two pointers hold the smallest and largest unused values; place the smallest on I and the largest on D

LeetCode 941 note: climb from the left to the peak, then descend; you must reach the end exactly, with the peak not at either end

LeetCode 938 note: prune with the BST order, going only right below low and only left above high, adding nodes inside the range

LeetCode 929 note: split at @, normalize only the local part (drop everything after +, remove dots), rejoin with the domain and collect in a set