@@ -248,7 +248,7 @@ void backtracking(参数) {
248248## 并查集
249249
250250```CPP
251- int n = 1005; // 更具题意而定
251+ int n = 1005; // 根据题意而定
252252 int father[1005];
253253
254254 // 并查集初始化
@@ -280,6 +280,263 @@ void backtracking(参数) {
280280(持续补充ing)
281281## 其他语言版本
282282
283+ JavaScript:
284+ 285+ ## 二分查找法
286+ 287+ 使用左闭右闭区间
288+ 289+ ``` javascript
290+ var search = function (nums , target ) {
291+ let left = 0 , right = nums .length - 1 ;
292+ // 使用左闭右闭区间
293+ while (left <= right) {
294+ let mid = left + Math .floor ((right - left)/ 2 );
295+ if (nums[mid] > target) {
296+ right = mid - 1 ; // 去左面闭区间寻找
297+ } else if (nums[mid] < target) {
298+ left = mid + 1 ; // 去右面闭区间寻找
299+ } else {
300+ return mid;
301+ }
302+ }
303+ return - 1 ;
304+ };
305+ ```
306+ 307+ 使用左闭右开区间
308+ 309+ ``` javascript
310+ var search = function (nums , target ) {
311+ let left = 0 , right = nums .length ;
312+ // 使用左闭右开区间 [left, right)
313+ while (left < right) {
314+ let mid = left + Math .floor ((right - left)/ 2 );
315+ if (nums[mid] > target) {
316+ right = mid; // 去左面闭区间寻找
317+ } else if (nums[mid] < target) {
318+ left = mid + 1 ; // 去右面闭区间寻找
319+ } else {
320+ return mid;
321+ }
322+ }
323+ return - 1 ;
324+ };
325+ ```
326+ 327+ ## KMP
328+ 329+ ``` javascript
330+ var kmp = function (next , s ) {
331+ next[0 ] = - 1 ;
332+ let j = - 1 ;
333+ for (let i = 1 ; i < s .length ; i++ ){
334+ while (j >= 0 && s[i] !== s[j + 1 ]) {
335+ j = next[j];
336+ }
337+ if (s[i] === s[j + 1 ]) {
338+ j++ ;
339+ }
340+ next[i] = j;
341+ }
342+ }
343+ ```
344+ 345+ ## 二叉树
346+ 347+ ### 深度优先遍历(递归)
348+ 349+ 二叉树节点定义:
350+ 351+ ``` javascript
352+ function TreeNode (val , left , right ) {
353+ this .val = (val === undefined ? 0 : val);
354+ this .left = (left === undefined ? null : left);
355+ this .right = (right === undefined ? null : right);
356+ }
357+ ```
358+ 359+ 前序遍历(中左右):
360+ 361+ ``` javascript
362+ var preorder = function (root , list ) {
363+ if (root === null ) return ;
364+ list .push (root .val ); // 中
365+ preorder (root .left , list); // 左
366+ preorder (root .right , list); // 右
367+ }
368+ ```
369+ 370+ 中序遍历(左中右):
371+ 372+ ``` javascript
373+ var inorder = function (root , list ) {
374+ if (root === null ) return ;
375+ inorder (root .left , list); // 左
376+ list .push (root .val ); // 中
377+ inorder (root .right , list); // 右
378+ }
379+ ```
380+ 381+ 后序遍历(左右中):
382+ 383+ ``` javascript
384+ var postorder = function (root , list ) {
385+ if (root === null ) return ;
386+ postorder (root .left , list); // 左
387+ postorder (root .right , list); // 右
388+ list .push (root .val ); // 中
389+ }
390+ ```
391+ 392+ ### 深度优先遍历(迭代)
393+ 394+ 前序遍历(中左右):
395+ 396+ ``` javascript
397+ var preorderTraversal = function (root ) {
398+ let res = [];
399+ if (root === null ) return rs;
400+ let stack = [root],
401+ cur = null ;
402+ while (stack .length ) {
403+ cur = stack .pop ();
404+ res .push (cur .val );
405+ cur .right && stack .push (cur .right );
406+ cur .left && stack .push (cur .left );
407+ }
408+ return res;
409+ };
410+ ```
411+ 412+ 中序遍历(左中右):
413+ 414+ ``` javascript
415+ var inorderTraversal = function (root ) {
416+ let res = [];
417+ if (root === null ) return res;
418+ let stack = [];
419+ let cur = root;
420+ while (stack .length !== 0 || cur !== null ) {
421+ if (cur !== null ) {
422+ stack .push (cur);
423+ cur = cur .left ;
424+ } else {
425+ cur = stack .pop ();
426+ res .push (cur .val );
427+ cur = cur .right ;
428+ }
429+ }
430+ return res;
431+ };
432+ ```
433+ 434+ 后序遍历(左右中):
435+ 436+ ``` javascript
437+ var postorderTraversal = function (root ) {
438+ let res = [];
439+ if (root === null ) return res;
440+ let stack = [root];
441+ let cur = null ;
442+ while (stack .length ) {
443+ cur = stack .pop ();
444+ res .push (cur .val );
445+ cur .left && stack .push (cur .left );
446+ cur .right && stack .push (cur .right );
447+ }
448+ return res .reverse ()
449+ };
450+ ```
451+ 452+ ### 广度优先遍历(队列)
453+ 454+ ``` javascript
455+ var levelOrder = function (root ) {
456+ let res = [];
457+ if (root === null ) return res;
458+ let queue = [root];
459+ while (queue .length ) {
460+ let n = queue .length ;
461+ let temp = [];
462+ for (let i = 0 ; i < n; i++ ) {
463+ let node = queue .shift ();
464+ temp .push (node .val );
465+ node .left && queue .push (node .left );
466+ node .right && queue .push (node .right );
467+ }
468+ res .push (temp);
469+ }
470+ return res;
471+ };
472+ ```
473+ 474+ ### 二叉树深度
475+ 476+ ``` javascript
477+ var getDepth = function (node ) {
478+ if (node === null ) return 0 ;
479+ return 1 + Math .max (getDepth (node .left ), getDepth (node .right ));
480+ }
481+ ```
482+ 483+ ### 二叉树节点数量
484+ 485+ ``` javascript
486+ var countNodes = function (root ) {
487+ if (root === null ) return 0 ;
488+ return 1 + countNodes (root .left ) + countNodes (root .right );
489+ }
490+ ```
491+ 492+ ## 回溯算法
493+ 494+ ``` javascript
495+ function backtracking (参数) {
496+ if (终止条件) {
497+ 存放结果;
498+ return ;
499+ }
500+ 501+ for (选择:本层集合中元素(树中节点孩子的数量就是集合的大小)) {
502+ 处理节点;
503+ backtracking (路径,选择列表); // 递归
504+ 回溯,撤销处理结果
505+ }
506+ }
507+ 508+ ```
509+ 510+ ## 并查集
511+ 512+ ``` javascript
513+ let n = 1005 ; // 根据题意而定
514+ let father = new Array (n).fill (0 );
515+ 516+ // 并查集初始化
517+ function init () {
518+ for (int i = 0 ; i < n; ++ i) {
519+ father[i] = i;
520+ }
521+ }
522+ // 并查集里寻根的过程
523+ function find (u ) {
524+ return u === father[u] ? u : father[u] = find (father[u]);
525+ }
526+ // 将v->u 这条边加入并查集
527+ function join (u , v ) {
528+ u = find (u);
529+ v = find (v);
530+ if (u === v) return ;
531+ father[v] = u;
532+ }
533+ // 判断 u 和 v是否找到同一个根
534+ function same (u , v ) {
535+ u = find (u);
536+ v = find (v);
537+ return u === v;
538+ }
539+ ```
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284541Java:
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