利用堆栈： http://oj.leetcode.com/problems/evaluate-reverse-polish-notation/ http://oj.leetcode.com/problems/longest-valid-parentheses/ （也可以用一维数组，贪心） http://oj.leetcode.com/problems/valid-parentheses/ http://oj.leetcode.com/problems/largest-rectangle-in-histogram/ 特别注意细节：http://oj.leetcode.com/problems/trapping-rain-water/
多种数据结构： http://oj.leetcode.com/problems/lru-cache/ http://oj.leetcode.com/problems/substring-with-concatenation-of-all-words/ (注意遍历方法） HASH：http://oj.leetcode.com/problems/longest-consecutive-sequence/
简单编程： http://oj.leetcode.com/problems/longest-common-prefix/ http://oj.leetcode.com/problems/string-to-integer-atoi/ (分析，控制语句）
排序 & 查找： 二分查找：http://oj.leetcode.com/problems/search-a-2d-matrix/ 二分查找进阶：http://oj.leetcode.com/problems/search-for-a-range/ 二分查找应用：http://oj.leetcode.com/problems/sqrtx/ 二分查找应用：http://oj.leetcode.com/problems/search-insert-position/ 二分查找变种：http://oj.leetcode.com/problems/search-in-rotated-sorted-array/ 二分查找变种：http://oj.leetcode.com/problems/search-in-rotated-sorted-array-ii/
简单数学： http://oj.leetcode.com/problems/pascals-triangle/ http://oj.leetcode.com/problems/pascals-triangle-ii/ http://oj.leetcode.com/problems/powx-n/ http://oj.leetcode.com/problems/reverse-integer/ http://oj.leetcode.com/problems/plus-one/ http://oj.leetcode.com/problems/unique-paths/ http://oj.leetcode.com/problems/palindrome-number/ http://oj.leetcode.com/problems/permutation-sequence/ http://oj.leetcode.com/problems/merge-intervals/ http://oj.leetcode.com/problems/valid-number/ http://oj.leetcode.com/problems/climbing-stairs/ http://oj.leetcode.com/problems/roman-to-integer/ http://oj.leetcode.com/problems/integer-to-roman/ http://oj.leetcode.com/problems/divide-two-integers/ 区间：http://oj.leetcode.com/problems/insert-interval/
大数的数学运算： http://oj.leetcode.com/problems/add-binary/ http://oj.leetcode.com/problems/add-two-numbers/
数组： http://oj.leetcode.com/problems/remove-element/ http://oj.leetcode.com/problems/merge-sorted-array/ http://oj.leetcode.com/problems/first-missing-positive/ http://oj.leetcode.com/problems/spiral-matrix/ http://oj.leetcode.com/problems/spiral-matrix-ii/ http://oj.leetcode.com/problems/rotate-image/ 遍历技巧：http://oj.leetcode.com/problems/container-with-most-water/ http://oj.leetcode.com/problems/two-sum/ http://oj.leetcode.com/problems/3sum/ http://oj.leetcode.com/problems/3sum-closest/ http://oj.leetcode.com/problems/4sum/ http://oj.leetcode.com/problems/set-matrix-zeroes/ 用好标记数组：http://oj.leetcode.com/problems/valid-sudoku/ http://oj.leetcode.com/problems/next-permutation/ http://oj.leetcode.com/problems/word-search/ http://oj.leetcode.com/problems/remove-duplicates-from-sorted-array/ http://oj.leetcode.com/problems/remove-duplicates-from-sorted-array-ii/ http://oj.leetcode.com/problems/sort-colors/
暴力方法/细节实现： http://oj.leetcode.com/problems/max-points-on-a-line/
链表： 归并排序：http://oj.leetcode.com/problems/sort-list/ 插入排序：http://oj.leetcode.com/problems/insertion-sort-list/ 反转、插入：http://oj.leetcode.com/problems/reorder-list/ 检测是否有环：http://oj.leetcode.com/problems/linked-list-cycle/ 确定链表环的起点：http://oj.leetcode.com/problems/linked-list-cycle-ii/ Deep Copy 带有随机指针的链表：http://oj.leetcode.com/problems/copy-list-with-random-pointer/ 链表细节：http://oj.leetcode.com/problems/rotate-list/ http://oj.leetcode.com/problems/remove-duplicates-from-sorted-list/ 删除细节：http://oj.leetcode.com/problems/remove-duplicates-from-sorted-list-ii/ http://oj.leetcode.com/problems/partition-list/ http://oj.leetcode.com/problems/swap-nodes-in-pairs/ Merge 两个链表：http://oj.leetcode.com/problems/merge-two-sorted-lists/ Merge 多链表：http://oj.leetcode.com/problems/merge-k-sorted-lists/ 细节：http://oj.leetcode.com/problems/reverse-nodes-in-k-group/ http://oj.leetcode.com/problems/remove-nth-node-from-end-of-list/ http://oj.leetcode.com/problems/reverse-linked-list-ii/
二叉树遍历：递归 & 非递归 http://oj.leetcode.com/problems/same-tree/ 前序：http://oj.leetcode.com/problems/binary-tree-preorder-traversal/ 中序：http://oj.leetcode.com/problems/binary-tree-inorder-traversal/ 后序：http://oj.leetcode.com/problems/binary-tree-postorder-traversal/ 遍历变种：http://oj.leetcode.com/problems/sum-root-to-leaf-numbers/ 遍历变种：http://oj.leetcode.com/problems/path-sum/ 遍历变种：http://oj.leetcode.com/problems/path-sum-ii/ 遍历变种：http://oj.leetcode.com/problems/maximum-depth-of-binary-tree/ 遍历变种：http://oj.leetcode.com/problems/minimum-depth-of-binary-tree/ 重建二叉树：http://oj.leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/ 重建二叉树：http://oj.leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/ 层次遍历变种：http://oj.leetcode.com/problems/binary-tree-zigzag-level-order-traversal/ 遍历变种：http://oj.leetcode.com/problems/symmetric-tree/ 遍历应用：http://oj.leetcode.com/problems/binary-tree-maximum-path-sum/ 遍历应用：http://oj.leetcode.com/problems/balanced-binary-tree/ 遍历应用：http://oj.leetcode.com/problems/recover-binary-search-tree/ 遍历应用：http://oj.leetcode.com/problems/flatten-binary-tree-to-linked-list/ level遍历：http://oj.leetcode.com/problems/binary-tree-level-order-traversal/ level 遍历：http://oj.leetcode.com/problems/binary-tree-level-order-traversal-ii/ level 遍历变种：http://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node/ level 遍历变种：http://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/
问题分析/智商/细节： http://oj.leetcode.com/problems/single-number/ http://oj.leetcode.com/problems/single-number-ii/ http://oj.leetcode.com/problems/candy/ ？ http://oj.leetcode.com/problems/gas-station/
动态规划： http://oj.leetcode.com/problems/triangle/ （最短路径） http://oj.leetcode.com/problems/subsets/ （另一种形式） http://oj.leetcode.com/problems/subsets-ii/ http://oj.leetcode.com/problems/edit-distance/ （经典） http://oj.leetcode.com/problems/word-break/ http://oj.leetcode.com/problems/word-break-ii/ http://oj.leetcode.com/problems/unique-binary-search-trees/ （动态规划避免递归） http://oj.leetcode.com/problems/unique-paths-ii/ http://oj.leetcode.com/problems/scramble-string/ http://oj.leetcode.com/problems/palindrome-partitioning/ http://oj.leetcode.com/problems/palindrome-partitioning-ii/ http://oj.leetcode.com/problems/interleaving-string/ http://oj.leetcode.com/problems/distinct-subsequences/ http://oj.leetcode.com/problems/decode-ways/ http://oj.leetcode.com/problems/gray-code/ http://oj.leetcode.com/problems/minimum-path-sum/
回溯： http://oj.leetcode.com/problems/combinations/ http://oj.leetcode.com/problems/generate-parentheses/ http://oj.leetcode.com/problems/combination-sum/ http://oj.leetcode.com/problems/combination-sum-ii/ http://oj.leetcode.com/problems/sudoku-solver/ 经典N皇后：http://oj.leetcode.com/problems/n-queens/ http://oj.leetcode.com/problems/n-queens-ii/ http://oj.leetcode.com/problems/letter-combinations-of-a-phone-number/
贪心： http://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock/ http://oj.leetcode.com/problems/jump-game/ http://oj.leetcode.com/problems/jump-game-ii/ http://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/ http://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/ http://oj.leetcode.com/problems/maximum-subarray/ http://oj.leetcode.com/problems/minimum-window-substring/ http://oj.leetcode.com/problems/maximal-rectangle/ http://oj.leetcode.com/problems/longest-substring-without-repeating-characters/
分治 & 递归： http://oj.leetcode.com/problems/unique-binary-search-trees-ii/ http://oj.leetcode.com/problems/restore-ip-addresses/ （时间复杂度有限，递归满足） http://oj.leetcode.com/problems/permutations/ http://oj.leetcode.com/problems/permutations-ii/ http://oj.leetcode.com/problems/convert-sorted-array-to-binary-search-tree/ http://oj.leetcode.com/problems/convert-sorted-list-to-binary-search-tree/ http://oj.leetcode.com/problems/median-of-two-sorted-arrays/ http://oj.leetcode.com/problems/validate-binary-search-tree/
字符串： http://oj.leetcode.com/problems/count-and-say/ http://oj.leetcode.com/problems/implement-strstr/ （子串查找） http://oj.leetcode.com/problems/anagrams/ http://oj.leetcode.com/problems/text-justification/ (细节） http://oj.leetcode.com/problems/simplify-path/ （基础控制语句 if-else-for） http://oj.leetcode.com/problems/multiply-strings/ http://oj.leetcode.com/problems/regular-expression-matching/ http://oj.leetcode.com/problems/wildcard-matching/ http://oj.leetcode.com/problems/longest-palindromic-substring/ http://oj.leetcode.com/problems/zigzag-conversion/ http://oj.leetcode.com/problems/length-of-last-word/ http://oj.leetcode.com/problems/valid-palindrome/
图： 深搜/广搜：http://oj.leetcode.com/problems/clone-graph/
搜索 & 遍历： http://oj.leetcode.com/problems/word-ladder/ http://oj.leetcode.com/problems/word-ladder-ii/ 广搜：http://oj.leetcode.com/problems/surrounded-regions/
