给一个 bst和一个double, 问你能不能找到一个值,和target的值最相近. 很naive的解法.在二叉遍历的同时, 记录当前节点值合给的值的差. public int closestValue(TreeNode root, double target) { int res = root.val; while(root != null){ if(Math.abs(root.val – target) < Math.abs(res – target)) res = root.val; if(root.val < target) root = root.right; else root = root.left; } return res; }  

For example, Given s = “the sky is blue“, return “blue is sky the“. 翻转一个string, 但是里面单词不翻转. 三步: 翻转整个string 用left记录每个单词开始的地方, 然后扫到空格就翻转一下. 最后记得翻转一下最后的string public void reverseWords(char[] s) { reverse(s,0,s.length-1); int left = 0; for(int i = 0 ; i < s.length; i++) { if(s[i] == ‘ ‘){ reverse(s, left, i-1); left = i+1; } } reverse(s, left, […]