Dynamic-Programming

LeetCode 264 note: three pointers mark the next ugly numbers to multiply by 2, 3 and 5; take the minimum each time and advance every pointer that produced it

LeetCode 647 note: expand around centers, counting one palindromic substring for each successful expansion

LeetCode 131 note: each level cuts a palindrome from the front of the remaining string, trying every length from 1 to the whole remainder

LeetCode 42 note: each cell holds min(tallest on the left, tallest on the right) - its own height; use prefix and suffix maxima or two pointers

LeetCode 5 note: expand around centers, using each position as an odd and an even center; with interval DP, iterate i from large to small

LeetCode 1137 note: like Fibonacci, roll three variables; watch the base values T0 = 0, T1 = T2 = 1 and the loop range

LeetCode 1025 note: dp[i] holds when some divisor x of i makes dp[i - x] a loss; observing the pattern, the answer is simply whether n is even

LeetCode 509 note: the starting point of 1D DP; only the previous two terms are needed, so roll two variables

LeetCode 392 note: two pointers; the pointer on t always advances, and the one on s advances on a match; bound-check both

LeetCode 119 note: only row rowIndex is needed; update a 1D array from right to left for O(k) space

LeetCode 118 note: each row starts and ends with 1, and every inner cell is the sum of the two cells above it