LeetCode

LeetCode 1431 note: compute the maximum once; a kid is True when their candies plus the extra reach >= the maximum, since a tie counts

LeetCode 3487 note: free deletion means picking distinct values; take every non-negative one, or only the maximum when all are negative

LeetCode 2487 note: the kept nodes are non-increasing left to right; keep a monotonic stack, pop anything smaller than the new node, then link what remains

LeetCode 3136 note: length at least 3, alphanumeric only, at least one vowel and at least one consonant; digits are not consonants

LeetCode 2000 note: find the first index i of ch, reverse word[:i + 1] and append the rest; return the word unchanged if ch is absent

LeetCode 3131 note: every element gets the same x, so x is the difference of the two minimums (or of the sums divided by the length)

LeetCode 3121 note: track each letter’s last lowercase index and first uppercase index; it counts only when the former comes first

LeetCode 3120 note: collect the letters seen in lowercase and in uppercase; the size of their intersection is the answer

LeetCode 735 note: scan left to right with a stack; only a right-moving top meeting a left-moving asteroid collides, the smaller explodes and equal sizes both do

LeetCode 988 note: DFS prepending each character so the string at a leaf already reads leaf to root, and keep the smallest

LeetCode 1814 note: rearrange the condition into nums[i] - rev(nums[i]) == nums[j] - rev(nums[j]), count pairs per value, and remember the modulus

LeetCode 3075 note: choose k children from the happiest, where the i-th choice loses i, floored at 0