LintCode 97 · Maximum Depth of Binary Tree.py

LintCode 683 · Word Break III.java

LintCode 1449 · Loud and Rich.java

LintCode 1360 · Symmetric Tree.java

Binary Search:
note that: "Check the left.left equal to the right.right."

LeetCode 200. Number of Islands.java

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Example 1:

Input:
11110
11010
11000
00000

Output: 1

Example 2:

Input:
11000
11000
00100
00011

Output: 3

LeetCode 339. Nested List Weight Sum

https://leetcode.com/problems/nested-list-weight-sum/submissions/

Example 1:

Input: [[1,1],2,[1,1]]
Output: 10 
Explanation: Four 1's at depth 2, one 2 at depth 1.

Example 2:

Input: [1,[4,[6]]]
Output: 27 
Explanation: One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4*2 + 6*3 = 27.

Ch5 DFS - Bootstrap your algorithms.

As we all know BFS and DFS are the famous two pillars of the Searching algorithms.

Now as we all know BFS can be easily accomplished with a simple Queue. Or let's say a FIFO data structure.

But the DFS remains a tricky one, for we actually usually keep the main function concise and just call a beefy helper function to get it done.

Of course somebody will raise their hand and say "Why not just use recursion?"
Baby, recursion and iterations are not algorithms themselves, however they remains two different styles of implementing the same algorithms.

Now talk is cheap, show me the code: