Easy

LeetCode 3750 note: compare the binary string with its reverse bit by bit; the number of mismatches is the answer

LeetCode 3731 note: the minimum and maximum are still present, so check every integer in between against a set

LeetCode 3712 note: count each value, and for counts divisible by k add value × count

LeetCode 3707 note: accumulate the left score while scanning, with the right side as total minus left; scores are alphabet positions 1 to 26, not ord

LeetCode 3701 note: add even indices and subtract odd ones; with slices, sum(nums[::2]) - sum(nums[1::2])

LeetCode 3697 note: each non-zero digit times its place value is one component; output them from the highest place down

LeetCode 3688 note: OR only the even numbers; the starting value 0 is also the answer when there are none

LeetCode 2264 note: there are only ten candidates, “000” to “999”, so check from “999” down whether each appears

LeetCode 3643 note: flip only the submatrix rows, swapping the slices of rows x + i and x + k - 1 - i

Solving the Valid Parentheses problem using stack-based approach

Monotonic decreasing stack over nums2 to build next-greater map; answer queries for nums1.

LeetCode Problem Solving