Easy

LeetCode 1018 note: each new bit turns the prefix into x = 2x + bit, so keep only x mod 5 and the number never grows

LeetCode 1013 note: the total must be divisible by 3; accumulate from the left, cutting whenever the running sum hits total / 3, and succeed with at least 3 pieces

LeetCode 1005 note: negate the smallest value each time; once the smallest is positive, only the parity of the remaining count matters

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