2019-04-09

LeetCode/Minimum Cost to Merge Stones

Problem Summary

There are N piles of stones in a row. The i-th pile has Xi stones.

A move consists of merging exactly K consecutive piles into one pile, and the cost of this move is equal to the total number of stones in these K piles.

Find the minimum cost to merge all piles of stones into one pile. If impossible, return -1.

2019-04-02

Algorithm

LeetCode/Lexicographical Numbers

Problem Summary

Given an integer n, return all numbers in [1,n] in lexicographical order.

n ≤ 5,000,000.

2019-03-29

Algorithm

LeetCode/Knight Dialer

Problem Summary

Place a knight on a phone pad, and let it hop N-1 times between the numbered keys, generating a N-digit number. Find how many distinct numbers we can dial in this manner.

2019-03-29

Algorithm

LeetCode/Regions Cut by Slashes

Problem Summary

Given a N × N grid of 1 × 1 squares, each square consists of a ‘/‘, ‘\’, or blank space. Find the number of regions.

2017-11-29

Algorithm

LeetCode/Edit Distance

Problem Summary

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)

2017-11-19

Algorithm

LeetCode/Validate Binary Search Tree

Problem Summary

Given a binary tree, determine if it is a binary search tree.

2017-11-13

Algorithm

LeetCode/Happy Number

Problem Summary

Write an algorithm to determine if a number is “happy”.

2017-11-12

Algorithm

LeetCode/Minimum Height Tree

Problem Summary

For an undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, find all roots of the MHTs.