Math

LeetCode 3824 note: binary search on k with a monotonic check; the upper bound must reach n because there are at least n operations

LeetCode 976 note: after sorting, check consecutive triples from the largest down; the first with a + b > c gives the largest perimeter

LeetCode 633 note: converge a from 0 and b from isqrt(c); shrink b when the sum is too big and grow a when it is too small; watch for 0, a == b, and floating-point square roots

LeetCode 1040 note: max moves = total gaps minus the edge gap the first move wastes; min moves uses a length-n window holding the most stones, with a special case of 2 when n - 1 stones are already consecutive and one is far away

LeetCode 3805 note: shift each string so its first letter is a, making Caesar-equivalent strings identical, then count pairs per normalized form

LeetCode 1401 note: the rectangle’s nearest point to the center is the center clamped into the rectangle; they overlap when that point is within the radius

LeetCode 2269 note: convert the number to a string and check every length-k substring; 0 cannot be a divisor

LeetCode 1281 note: walk the digits once, accumulating product and sum, and return product minus sum

LeetCode 1512 note: count while scanning; each number pairs with every earlier equal number, so add its current count to the answer

LeetCode 1486 note: generate start + 2i by definition and XOR them together

LeetCode 2469 note: apply the formulas directly, Kelvin = C + 273.15 and Fahrenheit = C × 1.8 + 32

LeetCode 2413 note: lcm(2, n), which is n when n is even and 2n when odd