LeetCode

LeetCode 3613 note: add edges from light to heavy; the weight when exactly k components remain is the answer, and 0 when n <= k

LeetCode 3612 note: simulate the four operations with a list; put the “result is non-empty” check inside the * branch, or * gets appended as a letter

LeetCode 2410 note: sort both sides, then same-direction pointers match the weakest player with the smallest trainer that is good enough

LeetCode 1353 note: each day, attend the event that ends earliest, using a min-heap of end days

LeetCode 3608 note: add edges back from the largest time; the time of the first edge that drops the component count below k is the answer

LeetCode 3607 note: Union-Find groups, one min-heap per group, and lazy deletion for offline stations

LeetCode 3606 note: filter valid coupons, then sort by (category order, code); character ranges must include z, Z and 9

LeetCode 3572 note: keep the largest y for each x, then take the three largest

LeetCode 3550 note: check indices in increasing order, computing each digit sum; the first match is the answer

LeetCode 1979 note: find the minimum and maximum, then take their GCD with Euclid’s algorithm

LeetCode Problem Solving

LeetCode 2094 note: enumerate the even numbers 100 to 998 instead and check that each digit needed is available; Counter subtraction keeps only positives