鍒烽绡?-鐑HOT 61-70

Posted 2021-03-17

鏍囩锛?a href='http://www.mamicode.com/so/1/%e5%8f%a6%e4%b8%80%e4%b8%aa' title='鍙︿竴涓?>鍙︿竴涓?/a>   rod   ddl   Fix   缁撴瀯   tree   The   璁＄畻   鐩存帴   

207.璇剧▼琛?/p>

鐜板湪浣犳€诲叡鏈?n 闂ㄨ闇€瑕侀€夛紝璁颁负 0 鍒?n-1銆傚湪閫変慨鏌愪簺璇剧▼涔嬪墠闇€瑕佷竴浜涘厛淇绋嬨€?渚嬪锛屾兂瑕佸涔犺绋?0 锛屼綘闇€瑕佸厛瀹屾垚璇剧▼ 1 锛屾垜浠敤涓€涓尮閰嶆潵琛ㄧず浠栦滑: [0,1]缁欏畾璇剧▼鎬婚噺浠ュ強瀹冧滑鐨勫厛鍐虫潯浠讹紝鍒ゆ柇鏄惁鍙兘瀹屾垚鎵€鏈夎绋嬬殑瀛︿範锛?/p>

绀轰緥 1:杈撳叆: 2, [[1,0]],杈撳嚭: true,瑙ｉ噴: 鎬诲叡鏈?2 闂ㄨ绋嬨€傚涔犺绋?1 涔嬪墠锛屼綘闇€瑕佸畬鎴愯绋?0銆傛墍浠ヨ繖鏄彲鑳界殑銆?/span>

绀轰緥 2:杈撳叆: 2, [[1,0],[0,1]]杈撳嚭: false,瑙ｉ噴: 鎬诲叡鏈?2 闂ㄨ绋嬨€傚涔犺绋?1 涔嬪墠锛屼綘闇€瑕佸厛瀹屾垚?璇剧▼ 0锛涘苟涓斿涔犺绋?0 涔嬪墠锛屼綘杩樺簲鍏堝畬鎴愯绋?1銆傝繖鏄笉鍙兘鐨勩€?br />
鍒嗘瀽锛氳繖涓棶棰樼浉褰撲簬鏌ユ壘涓€涓惊鐜槸鍚﹀瓨鍦ㄤ簬鏈夊悜鍥句腑锛屽彲浣跨敤BFS/DFS锛屾湰浣撳厛浣跨敤BFS锛屾槗浜庣悊瑙ｃ€傚浣曞垽鏂竴闂ㄨ绋嬭兘澶熷涔?-杩欓棬璇剧▼涓嶇敤鍏堜慨璇剧▼锛屾垨鑰呭厛淇绋嬪凡缁忓畬鎴愶紝鎴戜滑灏嗗凡缁忎慨瀹岀殑璇剧▼鐩存帴鎶涘純鍙備笌浠ュ悗鐨勮璁恒€備竴闂ㄨ绋嬬殑鍏堜慨璇剧▼鏁板嵆浣?lsquo;’鍏ュ害‘锛屽綋鍏ュ害涓?鏃讹紝灏辫鏄庤繖闂ㄨ绋嬪彲浠ュ畬鎴愶紝鎵€浠ユ垜浠鍏堝垱寤轰竴涓猟egree鏁扮粍瀛樺偍姣忛棬璇剧▼鐨勫叆搴︺€傚綋涓€涓湁鍚戝浘涓笉瀛樺湪鐜紝閭ｄ箞鍒氬紑濮嬫椂鑲畾鏈変竴涓叆搴︿负0锛屽嵆娌℃湁鍏堜慨璇剧▼鐨勮绋嬨€傛垜浠互姝よ绋嬭繘琛屽箍搴﹂亶鍘嗐€傛病閬嶅巻鍒颁竴闂ㄨ绋嬶紝閭ｄ箞璇存槑姝ゆ潯璺緞鍙揪锛岄偅涔堣繖闂ㄨ绋嬬殑鍏ュ害鍑忎竴锛屽鏋滃叆搴﹀彉涓?锛岃鏄庢璇剧▼涓嶅湪鐜唴锛屽緟瀹屾垚璇剧▼鏁板噺涓€銆傛渶鍚庢煡鐪嬪緟瀹屾垚璇剧▼鏄惁涓?.濡備綍瀹炵幇閬嶅巻鍛紝浣跨敤闃熷垪锛屽厛杩涘厛鍑?/p>

瀹炰緥锛歞egree[] = {0 ,0 ,1, 1, 2, 1}

 

浠ヨ绋?涓哄嚭鍙戠偣閬嶅巻鏈夊簭鍥撅紝灏嗚绋?鏀惧叆闃熷垪銆傛鏃舵爤鍐咃細1

 

鍑烘爤锛岄亶鍘?span style="color: #000000;">prerequisites[][]锛屽彂鐜拌绋?鐨勫厛淇绋嬫槸1锛岄偅涔堝氨灏哾egree[2] -1锛屾鏃禿egree[2]=0锛岄偅涔堣鏄?鍏ュ害涓?锛屽彲瀹屾垚锛屽叆鏍堛€傛鏃舵爤鍐咃細2

鍑烘爤锛岄亶鍘?span style="color: #000000;">prerequisites[][]锛屽彂鐜拌绋?鐨勫厛淇绋嬫槸2锛岄偅涔堝氨灏哾egree[3 ]-1锛屾鏃禿egree[3]=0锛岄偅涔堣鏄?鍏ュ害涓?锛屽彲瀹屾垚锛屽叆鏍堛€傛鏃舵爤鍐咃細3

 

锛堟澶勪笉鐢ㄥ嚭鏍堬紝鍥犱负杩樺湪浠ヨ绋?涓哄叆搴︾殑寰幆鍐咃級閬嶅巻prerequisites[][]锛屽彂鐜拌绋?鐨勫厛淇绋嬫槸2锛岄偅涔堝氨灏哾egree[4] -1锛屾鏃禿egree[4]=1锛岄偅涔堣鏄?鍏ュ害涓?锛屽彲瀹屾垚锛屽叆鏍堛€傛鏃舵爤鍐咃細3锛?

 

鍑烘爤锛岄亶鍘?span style="color: #000000;">prerequisites[][]锛屽彂鐜拌绋?鐨勫厛淇绋嬫槸3锛岄偅涔堝氨灏哾egree[5 ]-1锛屾鏃禿egree[5]=1锛岄偅涔堣鏄?鍏ュ害涓?锛屼笉鍙畬鎴愩€傛鏃舵爤鍐咃細4

鍑烘爤锛岄亶鍘?span style="color: #000000;">prerequisites[][]锛屽彂鐜拌绋?鐨勫厛淇绋嬫槸4锛岄偅涔堝氨灏哾egree[5 ]-1锛屾鏃禿egree[5]=0锛岄偅涔堣鏄?鍏ュ害涓?锛屽彲瀹屾垚銆傚叆鏍堬紝姝ゆ椂鏍堝唴锛?

鍑烘爤锛岄亶鍘?span style="color: #000000;">prerequisites[][]锛?/span>鍙戠幇娌℃湁浠?涓哄厛淇绋嬬殑锛岄偅涔堢粨鏉熷惊鐜€傛鏃堕槦鍒椾篃涓虹┖锛岄偅涔堢粨鏉熷惊鐜€傚垽鏂鏃跺緟淇绋嬫槸鍚︿负0锛?/span>

 

 1 class Solution {
 2     public boolean canFinish(int numCourses, int[][] prerequisites) {
 3         //璁＄畻鍏ュ害鏁扮粍
 4         int[] degree = new int[numCourses];
 5         for(int[] cp : prerequisites){
 6             degree[cp[0]]++;
 7         }
 8         //瀛樻斁鍏ュ害涓?璇剧▼
 9         LinkedList<Integer> queue = new LinkedList();
10         //鎵惧嚭鍏ュ害涓?鐨勮绋?/span>
11         for(int i=0;i<numCourses;i++){
12             if(degree[i]==0) queue.addLast(i);
13         }
14         //鎵惧埌涓嬩竴涓叆搴︿负0鐨?/span>
15         while(!queue.isEmpty()){
16             //鍑烘爤锛岃兘澶熷畬鎴愮殑璇剧▼
17             Integer pre = queue.removeFirst();
18             numCourses--;
19             for(int[] req : prerequisites){
20                 if(req[1] != pre) continue;
21                 degree[req[0]]--;
22                 if(degree[req[0]] == 0) queue.addLast(req[0]);
23             }
24         }
25         return numCourses==0;
26     }
27 }

 

 

 

208.瀹炵幇Trie锛堝墠缂€鏍戯級

瀹炵幇涓€涓?Trie (鍓嶇紑鏍?锛屽寘鍚?insert, search, 鍜?startsWith 杩欎笁涓搷浣溿€?br />绀轰緥:
Trie trie = new Trie();
trie.insert("apple");
trie.search("apple");   // 杩斿洖 true
trie.search("app");     // 杩斿洖 false
trie.startsWith("app"); // 杩斿洖 true
trie.insert("app");   
trie.search("app");     // 杩斿洖 true

鍒嗘瀽锛歍rie鏍硅妭鐐逛笉瀛樺叆鍊?/p>

1.Trie鑺傜偣缁撴瀯锛氫竴涓猧nt[26]鏁扮粍鏉ュ瓨鍌ㄥ瓧绗﹀€硷紝涓€涓猙oolean绫诲瀷is_end鍒ゆ柇鏄惁浠ヨ瀛楃缁撳熬銆備笅鍥捐〃绀簂eet鍦ㄦ爲涓殑琛ㄧず銆?/p>

 

 2.鎻掑叆锛氭彃鍏ヤ竴涓€硷紝浠庢牴閮ㄥ紑濮嬫悳绱㈠瓧绗﹀€硷紝瀛樺湪涓ょ鎯呭喌锛?/p>

銆€銆€銆€銆€閾炬帴瀛樺湪锛氱户缁悜涓嬫悳绱?/p>

銆€銆€銆€銆€閾炬帴涓嶅瓨鍦細鍒涘缓鏂拌妭鐐癸紝鐩村埌杈惧埌鎻掑叆鍊兼渶鍚庝竴涓瓧绗︼紝灏嗘湯灏惧瓧绗s_end璁剧疆涓簍rue

3.鏌ユ壘锛?/p>

 

 4.鍓嶇紑

 

 

 1 class TrieNode{
 2     TrieNode[] chiled;//璁板綍瀛╁瓙鑺傜偣
 3     boolean is_end;
 4     TrieNode(){
 5         chiled = new TrieNode[26];//涓€涓瀛愯妭鐐规湁2266涓垎鏀紝鍗充竴灞傛爲鏈?6鍚勫垎鏀?/span>
 6         is_end = false;
 7     }
 8 }
 9 class Trie {
10     TrieNode root;//鏍硅妭鐐癸紝涓嶅瓨鍊?/span>
11     /** Initialize your data structure here. */
12     public Trie() {
13         root = new TrieNode();
14     }
15     
16     /** Inserts a word into the trie. */
17     public void insert(String word) {
18         TrieNode node = root;
19         for(int i=0;i<word.length();i++){
20             char c = word.charAt(i);
21             if(node.chiled[c-鈥榓鈥榏==null){//濡傛灉璇ュ眰璇ュ瓧绗︿綅缃负绌?鍒欐柊寤轰竴涓?/span>
22                 node.chiled[c-鈥榓鈥榏 = new TrieNode();
23             }
24             node = node.chiled[c-鈥榓鈥榏;//鎸囧悜涓嬩竴灞?/span>
25         }
26         node.is_end = true;//瀛楃涓叉渶鍚庝竴涓瓧绗﹂偅灞傜殑浣嶇疆is_end=true
27     }
28     
29     /** Returns if the word is in the trie. */
30     public boolean search(String word) {
31         TrieNode node = root;
32         for(int i=0;i<word.length();i++){
33             char c= word.charAt(i);
34             if(node.chiled[c-鈥榓鈥榏 == null){//鍒ゆ柇鏄惁瀛樺湪
35                 return false;
36             }
37             node = node.chiled[c-鈥榓鈥?span style="color: #000000;">];
38         }
39         return node.is_end;//鍒ゆ柇缁撳熬
40     }
41     
42     /** Returns if there is any word in the trie that starts with the given prefix. */
43     /**
44     *serach鍜宻tartWith鍖哄埆鍦ㄤ簬鏄惁鍒ゆ柇缁撳熬is_end锛宻tartWith鏄彧瑕佸瓧绗﹀瓨鍦ㄥ氨琛?45     */
46     public boolean startsWith(String prefix) {
47         TrieNode node = root;
48         for(int i=0;i<prefix.length();i++){
49             char c= prefix.charAt(i);
50             if(node.chiled[c-鈥榓鈥榏 == null){//鍒ゆ柇鏄惁瀛樺湪
51                 return false;
52             }
53             node = node.chiled[c-鈥榓鈥?span style="color: #000000;">];
54         }
55         return true;
56     }
57 }
58 
59 /**
60  * Your Trie object will be instantiated and called as such:
61  * Trie obj = new Trie();
62  * obj.insert(word);
63  * boolean param_2 = obj.search(word);
64  * boolean param_3 = obj.startsWith(prefix);
65  */

 

215.鏁扮粍涓渶K涓渶澶у厓绱?/p>

绀轰緥 1:杈撳叆: [3,2,1,5,6,4] 鍜?k = 2锛岃緭鍑? 5
绀轰緥 2:杈撳叆: [3,2,3,1,2,4,5,5,6] 鍜?k = 4锛岃緭鍑? 4
鍒嗘瀽锛氭帓搴忥紝杈撳嚭nums[length-K]锛屽揩鎺扥(NlogN)锛涘鏉傚害涓嶅拫鍦帮紝鐪嬩簡棰樿В浣跨敤鍫嗘帓搴忥紝缁存寔涓€涓ぇ灏忎负K鐨勫皬椤跺爢锛岄偅涔堝爢椤跺氨鏄瓟妗堬紝濡傛灉澶т簬鍫嗛《涓斿爢婊″氨鍔犲叆锛屽弽涔嬩笉鎿嶄綔锛屽鏉傚害涓篛(NlogK)銆?/p>

 1 class Solution {
 2     public int findKthLargest(int[] nums, int k) {
 3         //鍒╃敤鏈€灏忓爢锛屽垱寤簁+1鐨剆ize锛岄亶鍘嗘暟缁勮繘琛屾坊鍔狅紝骞秔oll涓€涓?/span>
 4         PriorityQueue<Integer> heap = new PriorityQueue(k+1);
 5         for(int num : nums){
 6             heap.add(num);
 7             if(heap.size() > k){
 8                 heap.poll();
 9             }
10         }
11         return heap.poll();
12     }
13 }

 

221.鏈€澶ф鏂瑰舰

鍦ㄤ竴涓敱 0 鍜?1 缁勬垚鐨勪簩缁寸煩闃靛唴锛屾壘鍒板彧鍖呭惈 1 鐨勬渶澶ф鏂瑰舰锛屽苟杩斿洖鍏堕潰绉€?/p>

绀轰緥:

杈撳叆: 

1 0 1 0 0
1 0 1 1 1
1 1 1 1 1
1 0 0 1 0

杈撳嚭: 4

鍒嗘瀽锛氬姩鎬佽鍒掞紝寤虹珛涓€涓簩缁存暟缁刣p[i][j]锛屽湪宸︿笂瑙掔煩闃典腑鐢眒atrix[i-1][j-1]鍙備笌鏋勬垚鐨勬渶澶ф鏂瑰舰杈归暱銆?/p>

濡傛灉matrix[i-1][j-1]=鈥?鈥?nbsp; =>  dp[i][j] = min{dp[i-1][j], dp[i-1][j-1], dp[i][j-1] } +1銆傚惁鍒?dp[i][j]=0銆?/p>

 1 class Solution {
 2     public int maximalSquare(char[][] matrix) {
 3         if(matrix.length == 0) return 0;
 4         int rl = matrix.length;
 5         int cl = matrix[0].length;
 6         int[][] dp = new int[rl+1][cl+1];
 7         int maxLen = 0;
 8         for(int i=1;i<=rl;i++){
 9             for(int j=1;j<=cl;j++){
10                 if(matrix[i-1][j-1] == 鈥?鈥?span style="color: #000000;">){
11                     dp[i][j] = Math.min(dp[i-1][j-1], Math.min(dp[i-1][j],dp[i][j-1]))+1;
12                     maxLen = Math.max(maxLen, dp[i][j]);
13                 }
14             }
15         }
16         return maxLen*maxLen;
17     }
18 }

 

226.缈昏浆浜屽弶鏍?/p>

绀轰緥锛?br />
杈撳叆锛?br />
     4
   /  
  2     7
 /       /
1   3 6   9

杈撳嚭锛?br />
     4
   /  
  7     2
 /      /
9   6 3   1

鍒嗘瀽锛氶€掑綊

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 class Solution {
11     public TreeNode invertTree(TreeNode root) {
12         if(root == null){
13             return root;
14         }
15         TreeNode leftNode = invertTree(root.left);
16         TreeNode rightNode = invertTree(root.right);
17         root.left = rightNode;
18         root.right = leftNode;
19         return root;
20     }
21 }

 

杩唬

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if(root == null) return null;
        Queue<TreeNode> queue = new LinkedList();
        queue.add(root);
        while(!queue.isEmpty()){
            TreeNode node = queue.poll();
            TreeNode temp = node.left;
            node.left = node.right;
            node.right = temp;
            if(node.left!=null) queue.add(node.left);
            if(node.right!=null) queue.add(node.right);
        }
        return root;
    }
}

 

234.鍥炴枃閾捐〃

璇峰垽鏂竴涓摼琛ㄦ槸鍚︿负鍥炴枃閾捐〃銆?br />绀轰緥 1:杈撳叆: 1->2杈撳嚭: false
绀轰緥 2:杈撳叆: 1->2->2->1杈撳嚭: true
鍒嗘瀽锛?.蹇參鎸囬拡锛屾寚鍚戜腑闂淬€?.灏嗗墠鍗婃鍊掑簭銆?.閬嶅巻姣旇緝

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     int val;
 5  *     ListNode next;
 6  *     ListNode(int x) { val = x; }
 7  * }
 8  */
 9 class Solution {
10     public boolean isPalindrome(ListNode head) {
11         if(head == null || head.next == null) return true;
12         ListNode cur = head;
13         ListNode slow = head, fast = head.next, pre = null, prepre = null;
14         while(fast!=null&&fast.next!=null){
15             pre = slow;//鍏堜繚瀛榮low
16             slow = slow.next;
17             fast = fast.next.next;
18             //鍏堢Щ鍔ㄥ啀鍙嶈浆
19             pre.next = prepre;
20             prepre = pre;
21         }
22         ListNode p2 = slow.next;//鍙宠竟
23         slow.next = pre;
24         ListNode p1 = fast == null ? slow.next : slow;//濡傛灉鏄鏁颁釜锛屽垯璺宠繃涓棿鑺傜偣
25         while(p1 != null){
26             if(p1.val != p2.val) 
27                 return false;
28             p1 = p1.next;
29             p2 = p2.next;
30         }
31         return true;
32     }
33 }

 

 

236.浜屽弶鏍戠殑鏈€杩戝叕鍏辩鍏?/p>

缁欏畾涓€涓簩鍙夋爲, 鎵惧埌璇ユ爲涓袱涓寚瀹氳妭鐐圭殑鏈€杩戝叕鍏辩鍏堛€傜櫨搴︾櫨绉戜腑鏈€杩戝叕鍏辩鍏堢殑瀹氫箟涓猴細“瀵逛簬鏈夋牴鏍?T 鐨勪袱涓粨鐐?p銆乹锛屾渶杩戝叕鍏辩鍏堣〃绀轰负涓€涓粨鐐?x锛屾弧瓒?x 鏄?p銆乹 鐨勭鍏堜笖 x 鐨勬繁搴﹀敖鍙兘澶э紙涓€涓妭鐐逛篃鍙互鏄畠鑷繁鐨勭鍏堬級銆?rdquo;
渚嬪锛岀粰瀹氬涓嬩簩鍙夋爲:  root = [3,5,1,6,2,0,8,null,null,7,4]

绀轰緥 1:杈撳叆: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1锛涜緭鍑? 3锛岃В閲? 鑺傜偣 5 鍜岃妭鐐?1 鐨勬渶杩戝叕鍏辩鍏堟槸鑺傜偣 3銆?br />绀轰緥 2:杈撳叆: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4锛涜緭鍑? 5锛岃В閲? 鑺傜偣 5 鍜岃妭鐐?4 鐨勬渶杩戝叕鍏辩鍏堟槸鑺傜偣 5銆傚洜涓烘牴鎹畾涔夋渶杩戝叕鍏辩鍏堣妭鐐瑰彲浠ヤ负鑺傜偣鏈韩銆?br />鍒嗘瀽锛氶€掑綊锛屼粠鏍硅妭鐐瑰紑濮嬨€傚鏋滃瓨鍦ㄥ叕鍏辩鍏堬紝鎵€浠ヨ涔堟槸鏍硅妭鐐癸紝瑕佷箞鍦ㄥ乏瀛愭爲鎴栧彸瀛愭爲銆傚鏋滄牴鑺傜偣宸茬粡鍖呭惈寰呮眰鍊间腑鐨勬煇涓€鍊硷紝鍒欐牴鑺傜偣涓€瀹氭槸鏈€鏃╁叕鍏辩鍏堬紙涓€涓妭鐐瑰厛閬嶅巻鍒帮紝鍙︿竴涓妭鐐规槸鍏剁鍏堬級銆傞亶鍘嗚繃绋嬩腑锛屽瓨鍦ㄤ笁绉嶆儏鍐碉細

- 濡傛灉宸﹀瓙鏍戜腑娌℃湁寰呮眰鍊硷紝浣嗗彸瀛愭爲涓繑鍥炰簡鏌愪竴鑺傜偣鍊硷紝鍒欏彲鍒ゆ柇鍙冲瓙鏍戜腑瀛樺湪鍏叡瀛愯妭鐐癸紝鑰岄€掑綊鎿嶄綔灏卞彲浠ヨ揪鍒版煡鎵惧埌鏈€鏃╁叕鍏卞瓙鑺傜偣鐨勪綔鐢?/p>

- 濡傛灉宸﹀瓙鏍戜腑杩斿洖姣忎竴鑺傜偣锛岃€屽彸瀛愭爲涓负绌猴紝涓庝笂杩版儏鍐电浉鍚?/p>

- 濡傛灉宸﹀彸瀛愭爲鍧囨湁杩斿洖鑺傜偣锛屽垯鍙垽鏂乏鍙冲瓙鏍戜腑搴斿垎鍒湁涓€涓緟姹傝妭鐐癸紝鏁呮鏃剁殑鏍硅妭鐐逛竴瀹氭槸鏈€鏃╁叕鍏辩鍏堛€?/p>

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 class Solution {
11     public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
12         if(root == null || root == p || root == q){
13             return root;
14         }
15         //鏍规嵁褰撳墠鑺傜偣瀵绘壘宸﹀彸瀛愭爲
16         TreeNode left = lowestCommonAncestor(root.left,p,q);
17         TreeNode right = lowestCommonAncestor(root.right,p,q);
18         //濡傛灉宸﹀瓙鏍戞湁涓€涓紝鍙冲瓙鏍戜篃鎵惧埌涓€涓紝鍒欒繑鍥炲綋鍓嶈妭鐐?/span>
19         if(left!=null&&right!=null){
20             return root;
21         }
22         //宸﹀瓙鏍戞病鏈夛紝閭ｄ箞鍘诲彸瀛愭爲鎵?/span>
23         if(left == null) return right;
24         //涓庝笂杩扮浉鍙?/span>
25         if(right == null) return left;
26         return null;
27     }
28 }

 

238.闄よ嚜韬互澶栨暟缁勭殑涔樼Н

缁欏畾闀垮害涓?n 鐨勬暣鏁版暟缁?nums锛屽叾涓?n > 1锛岃繑鍥炶緭鍑烘暟缁?output 锛屽叾涓?output[i] 绛変簬 nums 涓櫎 nums[i] 涔嬪鍏朵綑鍚勫厓绱犵殑涔樼Н銆?br />绀轰緥:杈撳叆: [1,2,3,4],杈撳嚭: [24,12,8,6]
璇存槑: 璇蜂笉瑕佷娇鐢ㄩ櫎娉曪紝涓斿湪 O(n) 鏃堕棿澶嶆潅搴﹀唴瀹屾垚姝ら銆?/p>

鍒嗘瀽锛氭毚鍔涙硶涓嶅彲鍙栵紝O(N^2)銆備箻绉?= 褰撳墠鏁板乏杈逛箻绉?* 褰撳墠鏁板彸杈逛箻绉€傝缃竴鏁扮粍锛屼竴娆′粠澶村埌灏鹃亶鍘嗗師鏁扮粍瀛樺叆宸﹁竟涔樺€硷紝涓€娆′粠鏈埌澶撮亶鍘嗗師鏁扮粍瀛樺叆鍙宠竟涔樺€笺€備緥濡傦細[1,2,3,4]

浠庡墠寰€鍚庯細[1锛?*1锛?2*1锛?2*3]

浠庡悗寰€鍓嶏細[1*2*3*4锛?*1 * 3*4锛?*1 * 4锛?*3]

 1 class Solution {
 2     public int[] productExceptSelf(int[] nums) {
 3         int[] res = new int[nums.length];
 4         int k = 1;
 5         for(int i=0;i<nums.length;i++){
 6             res[i] = k;//[1,1,2,6]
 7             k *= nums[i];//[1,2,6,24]缁欎笅娆′箻鍊间娇鐢紝杩欐牱灏辨槸i宸﹁竟鐨勪箻鍊?/span>
 8         }
 9         k = 1;
10         for(int i=nums.length-1;i>=0;i--){
11             res[i] *= k;//[24,12,8,6]
12             k *= nums[i];//[24,24,12,4] i鍙宠竟鐨勪箻鍊?
13         }
14         return res;
15     }
16 }

 

239.婊戝姩绐楀彛鏈€澶у€?/p>

缁欏畾涓€涓暟缁?nums锛屾湁涓€涓ぇ灏忎负 k 鐨勬粦鍔ㄧ獥鍙ｄ粠鏁扮粍鐨勬渶宸︿晶绉诲姩鍒版暟缁勭殑鏈€鍙充晶銆備綘鍙彲浠ョ湅鍒板湪婊戝姩绐楀彛鍐呯殑 k 涓暟瀛椼€傛粦鍔ㄧ獥鍙ｆ瘡娆″彧鍚戝彸绉诲姩涓€浣嶃€傝繑鍥炴粦鍔ㄧ獥鍙ｄ腑鐨勬渶澶у€笺€?br />绀轰緥:
杈撳叆: nums = [1,3,-1,-3,5,3,6,7], 鍜?k = 3锛岃緭鍑? [3,3,5,5,6,7]
瑙ｉ噴:
  婊戝姩绐楀彛鐨勪綅缃?nbsp;               鏈€澶у€?br />---------------               -----
[1  3  -1] -3  5  3  6  7       3
 1 [3  -1  -3] 5  3  6  7       3
 1  3 [-1  -3  5] 3  6  7       5
 1  3  -1 [-3  5  3] 6  7       5
 1  3  -1  -3 [5  3  6] 7       6
 1  3  -1  -3  5 [3  6  7]      7

鎻愮ず锛氫綘鍙互鍋囪 k 鎬绘槸鏈夋晥鐨勶紝鍦ㄨ緭鍏ユ暟缁勪笉涓虹┖鐨勬儏鍐典笅锛? ≤ k ≤ 杈撳叆鏁扮粍鐨勫ぇ灏忋€?br />鍒嗘瀽锛氬弻鍚戦摼琛細鍓戞寚Offer锛?/p>

Step1.浣跨敤涓€涓弻绔槦鍒楀瓨鍌ㄦ粦绐楀唴鍏冪礌鐨勪笅鏍囥€?/span>

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

queue

 

Step2.鑻ueue涓虹┖锛岃鏄庡垰寮€濮嬫粦鍔紝灏唍um绗竴涓厓绱犵殑绱㈠紩鍘嬪叆闃熷垪涓€?/span>

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

銆€queue

0

 

Step3.閬嶅巻num涓嬩竴涓厓绱爊um[1]=3锛?/span>

銆€銆€鈶犲厛鍒ゆ柇褰撳墠绱㈠紩浣嶇疆鍑忓幓闃熷垪鏈€宸﹁竟鍏冪礌鏄惁>=size锛屽鏋滄槸锛岄偅涔堣鏄庨殢鐫€婊戠獥婊戝姩锛屽綋鍓嶆粦绐楀唴鐨勬渶澶у€兼粦鍑哄幓浜嗭紝宸茬粡涓嶅啀杩欎釜婊戠獥鍐咃紝杩欐槸闇€瑕佸皢闃熷垪鏈€宸﹁竟鍏冪礌寮瑰嚭銆傦紙闃熷垪鏈€宸﹁竟涓烘粦绐楀唴鏈€澶у€肩储寮曪紝鍒ゆ柇鏄惁鏈夋晥锛?/span>

銆€銆€鈶″皢褰撳墠鍏冪礌涓庨槦鍒楁渶鍙宠竟鐨勭储寮曞鐨勬暟缁勫€煎姣旓紝濡傛灉褰撳墠鍏冪礌澶т簬闃熷垪鏈€鍙宠竟瀵瑰簲鐨勫€硷紝鍒欏皢闃熷垪鏈€鍙宠竟鐨勫€煎脊鍑猴紝鐩村埌鎵惧埌瀵瑰簲鍊兼瘮褰撳墠鍏冪礌鍊煎ぇ鐨勩€傦紙闃熷垪宸﹁竟鏄渶澶х殑鍊硷紝闅忕潃涓婅堪鎿嶄綔锛屼細閫愭笎鏇存柊闃熷垪锛屾粦鍑哄幓鎴栬€呮柊娣诲姞鐨勫€兼洿澶х殑璇濆皢浼氭洿鏂伴槦鍒楋紝淇濊瘉闃熷ご瀵瑰簲鍊兼渶澶э級

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

1

 

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

2

---杈撳嚭4

 

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

2

3

---杈撳嚭4

 

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

4

---杈撳嚭6

 

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

4

5

---杈撳嚭6

 

value	2	3	4	2	6	2	5
index	0	1	2	3	4	5	6

 

4

5

---杈撳嚭6

 

value	2	3	4	2	6	2	5	1
index	0	1	2	3	4	5	6	7

 --褰撳墠绱㈠紩澶勪綅缃紙7锛?闃熷垪鏈€宸﹁竟锛?锛?size锛?锛?-銆嬫粦鍑?/span>

4

5

7

 --

5

7

 --杈撳嚭5

 琛ュ厖锛氶槦澶存槸瀛樺偍鏈€澶у€肩殑绱㈠紩锛岄槦澶磋寮瑰嚭鐨勬儏鍐碉細鏂版潵鐨勬瘮闃熷唴鎵€鏈夋暟閮藉ぇ銆侀槦澶翠笉鍦ㄥ綋鍓嶅瓙鏁扮粍涓€傛柊鏉ユ垚鍛樻椂锛屽垽鏂槸鍚︽湁鑰佹垚鍛樺お鑰佷簡鍜屾柊鎴愬憳鏄惁姣斿叾浠栬€佹垚鍛樺ぇ锛堝惊鐜瘮锛屽ぇ涓€涓脊涓€涓紝鐩村埌闃熷垪涓虹┖鎴栬€呮瘮鑰佹垚鍛樺皬锛夈€傞槦鍐呮儏鍐碉細绱㈠紩鐢卞皬鍒板ぇ锛屽洜涓轰綅浜庡綋鍓嶅厓绱犲墠闈㈠苟涓斿皬鐨勮娣樻卑浜嗐€?/span>

 

 1 class Solution {
 2     public int[] maxSlidingWindow(int[] nums, int k) {
 3         if(nums==null||nums.length==0) return nums;
 4         int len = nums.length;
 5         int[] res = new int[len-k+1];
 6         int index = 0;
 7         ArrayDeque<Integer> queue = new ArrayDeque<Integer>();//闃熷垪瀛樺偍鐨勬槸绱㈠紩鍊?/span>
 8         for(int i=0;i<nums.length;i++){
 9             if(queue.isEmpty()){
10                 queue.add(i);//鍒氬紑濮嬫椂
11             }
12             if(i-queue.peekFirst()>=k){
13                 queue.pollFirst();//灏嗗お鑰佺殑鑰佹垚鍛樻彁鍑?/span>
14             }
15             while(!queue.isEmpty() && nums[i]>=nums[queue.peekLast()]){
16                 queue.pollLast();
17             }
18             queue.addLast(i);
19             if(i>=k-1){//k-1涓厓绱犲紑濮嬶紝灏辫杈撳嚭浜?/span>
20                 res[index++] = nums[queue.peekFirst()];
21             }
22         }
23         return res;
24     }
25 }

 

 

 

 

240.鎼滅储浜岀淮鐭╅樀鈪?/p>

缂栧啓涓€涓珮鏁堢殑绠楁硶鏉ユ悳绱?m x n 鐭╅樀 matrix 涓殑涓€涓洰鏍囧€?target銆傝鐭╅樀鍏锋湁浠ヤ笅鐗规€э細姣忚鐨勫厓绱犱粠宸﹀埌鍙冲崌搴忔帓鍒椼€傛瘡鍒楃殑鍏冪礌浠庝笂鍒颁笅鍗囧簭鎺掑垪銆?br />绀轰緥:
鐜版湁鐭╅樀 matrix 濡備笅锛?br />[
  [1,   4,  7, 11, 15],
  [2,   5,  8, 12, 19],
  [3,   6,  9, 16, 22],
  [10, 13, 14, 17, 24],
  [18, 21, 23, 26, 30]
]
缁欏畾 target = 5锛岃繑鍥?true銆傜粰瀹?target = 20锛岃繑鍥?false銆?br />鍒嗘瀽锛氱煩闃电壒鐐癸細宸︿笂瑙掓渶灏忥紝鍙充笅瑙掓渶澶с€傛湰棰樹粠宸︿笅瑙掗亶鍘嗭紝濡傛灉澶т簬褰撳墠鍏冪礌锛屽垯鍚戝彸瀵绘壘锛屽弽涔嬶紝鍚戜笂瀵绘壘銆傚鏉傚害O(n+m)銆?/p>

 1 class Solution {
 2     public boolean searchMatrix(int[][] matrix, int target) {
 3         if(matrix == null || matrix.length ==0 || matrix[0].length == 0){
 4             return false;
 5         }
 6         int m = matrix.length;
 7         int n = matrix[0].length;
 8         int row = m-1, col = 0;
 9         while(row >= 0 && col <= n-1){
10             if(matrix[row][col] == target){
11                 return true;
12             }else if(matrix[row][col] < target){
13                 col++;
14             }else{
15                 row--;
16             }
17         }
18         return false;
19     }
20 }