Greedy

LeetCode 1989 note: process the “it” players left to right, each catching the leftmost uncaught person in range, with a right-only pointer to the next candidate

LeetCode 948 note: after sorting, buy score with the cheapest token and buy power with the most expensive one; trade for power only when score > 0, and stop when neither move works

LeetCode 2697 note: converging pointers, setting both ends to the smaller character whenever they differ

LeetCode 1877 note: after sorting, pair the smallest with the largest, the second smallest with the second largest, and take the largest pair sum with converging pointers

LeetCode 1616 note: greedily match a’s prefix against b’s suffix from the outside in; the leftover middle must be a palindrome entirely within a or b, and both directions need checking

LeetCode 3816 note: a monotonic stack that deletes a larger top while another copy exists, then trims duplicate letters off the end since a prefix is always smaller

LeetCode 3810 note: one operation fixes every position holding a value, so the answer is the number of distinct values at mismatched positions

LeetCode 3413 note: the best k bags always have one end on a segment boundary; compute “left end at a segment start” and “right end at a segment end” (the latter by mirroring and reusing the same function)

LeetCode 2271 note: starting the carpet at some segment’s start is never worse; after sorting, two pointers sum the fully covered segments and count the last one partially

LeetCode 1838 note: after sorting, raising the whole window to nums[right] costs nums[right] × length − window sum; shrink the left while that exceeds k

LeetCode 1975 note: minus signs can travel anywhere in pairs but the parity of the negative count never changes; with an odd count, leave one on the smallest absolute value

LeetCode 3800 note: split mismatches into two kinds; pair different kinds with a swap, same kinds with cross + swap, flip any leftover, and compare each against two flips