Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commitde7ba71

Browse files
committed
Continue dynamic programming 91, 152, 120 Tree 106 String 151
1 parent7499c58 commitde7ba71

File tree

8 files changed

+151
-0
lines changed

8 files changed

+151
-0
lines changed

‎Easy/104-maxDepth.js‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,3 +22,11 @@ var maxDepth = function(root) {
2222
}
2323
returnmax+1;
2424
}
25+
26+
// second try
27+
varmaxDepth=function(root){
28+
if(!root)return0;
29+
varlHeight=maxDepth(root.left)+1;
30+
varrHeight=maxDepth(root.right)+1;
31+
returnlHeight>rHeight ?lHeight :rHeight;
32+
};

‎Medium/106-constructBinaryTree.js‎

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
/**
2+
* Definition for a binary tree node.
3+
* function TreeNode(val) {
4+
* this.val = val;
5+
* this.left = this.right = null;
6+
* }
7+
*/
8+
/**
9+
*@param {number[]} inorder
10+
*@param {number[]} postorder
11+
*@return {TreeNode}
12+
*/
13+
varbuildTree=function(inorder,postorder){
14+
returnhelper(inorder,0,inorder.length-1,postorder,0,postorder.length-1);
15+
};
16+
17+
varhelper=function(inorder,inStart,inEnd,postorder,postStart,postEnd){
18+
if(inEnd<inStart||postEnd<postStart)returnnull;
19+
varrootVal=postorder[postEnd];
20+
varroot=newTreeNode(rootVal);
21+
for(vari=0;i<inEnd;i++){
22+
if(inorder[i]===rootVal){
23+
break;
24+
}
25+
}
26+
root.left=helper(inorder,inStart,i-1,postorder,postStart,postStart+i-1-inStart);
27+
root.right=helper(inorder,i+1,inEnd,postorder,postEnd-inEnd+i,postEnd-1);
28+
returnroot;
29+
};

‎Medium/114-flattenTree.js‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13,3 +13,18 @@ var flatten = function(root) {
1313
while(oRoot.right)oRoot=oRoot.right;
1414
oRoot.right=oRight;
1515
};
16+
17+
// 2nd try
18+
varflatten=function(root){
19+
if(!root)return;
20+
// save right now
21+
vartmp=root.right;
22+
flatten(root.left);
23+
flatten(root.right);
24+
root.right=root.left;
25+
root.left=null;
26+
while(root.right){
27+
root=root.right;
28+
}
29+
root.right=tmp;
30+
};

‎Medium/120-triangle.js‎

Lines changed: 33 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,33 @@
1+
/**
2+
* Dynamic programming
3+
*
4+
*@param {number[][]} triangle
5+
*@return {number}
6+
*/
7+
// straightforward, top-down, space O(N^2)
8+
varminimumTotal=function(triangle){
9+
vardp=[triangle[0]];
10+
for(vari=1;i<triangle.length;i++){
11+
// in JavaScript, remember to have a new array for each row.
12+
dp[i]=[];
13+
for(varj=0;j<triangle[i].length;j++){
14+
if(j===0)dp[i][j]=dp[i-1][j]+triangle[i][j];
15+
elseif(j===triangle[i].length-1)dp[i][j]=dp[i-1][j-1]+triangle[i][j];
16+
elsedp[i][j]=Math.min(dp[i-1][j-1],dp[i-1][j])+triangle[i][j];
17+
}
18+
}
19+
returnMath.min.apply(null,dp[triangle.length-1]);
20+
};
21+
22+
// bottom-up, space O(N)
23+
varminimumTotal=function(triangle){
24+
varlength=triangle.length;
25+
varsum=triangle[length-1];
26+
for(vari=length-2;i>=0;i--){
27+
for(varj=0;j<triangle[i].length;j++){
28+
sum[j]=Math.min(sum[j],sum[j+1])+triangle[i][j];
29+
}
30+
console.log(sum);
31+
}
32+
returnsum[0];
33+
};
Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
/**
2+
*@param {string} str
3+
*@returns {string}
4+
*/
5+
varreverseWords=function(str){
6+
varwords=str.split(' ');
7+
// the O(1) space
8+
varj=0;
9+
for(vari=0;i<words.length;i++){
10+
if(words[i]!==''){
11+
words[j]=words[i];
12+
j++;
13+
}
14+
}
15+
returnwords.slice(0,j).reverse().join(' ');
16+
};

‎Medium/152-MaxProductSubarray.js‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
/**
2+
* Solution: Two dp arrays: maxDP tracks the Maximum product at index i,
3+
* minDP tracks the Minimum product at index i, either of them can be negative Numbers
4+
* so if nums[i + 1] is negative, then maxDP[i+1] can be a product of minDP[i] * nums[i+1]
5+
*@see the for loop body
6+
*
7+
*@param {number[]} nums
8+
*@return {number}
9+
*/
10+
varmaxProduct=function(nums){
11+
if(nums.length===0)return0;
12+
varresult=nums[0];
13+
varmaxDP=[nums[0]];
14+
varminDP=[nums[0]];
15+
16+
for(vari=1;i<nums.length;i++){
17+
maxDP[i]=Math.max(nums[i],maxDP[i-1]*nums[i],minDP[i-1]*nums[i]);
18+
minDP[i]=Math.min(nums[i],minDP[i-1]*nums[i],maxDP[i-1]*nums[i]);
19+
result=Math.max(maxDP[i],result);
20+
}
21+
22+
returnresult;
23+
};

‎Medium/91-decodeways.js‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
1+
/**
2+
* solution: dp[i] = dp[i - 1] if s[i - 1] is valid (!= 0)
3+
* or dp[i] = dp[i-2] if s[i-1] is not valid, however s.substring(i-2, i) is valid ( >=10 && <=26)
4+
* or dp[i] = dp[i-1] + dp[i-2] is both s.substring(i-2, i), s.substring(i-1, i) are valid
5+
*
6+
*@param {string} s
7+
*@return {number}
8+
*/
9+
varnumDecodings=function(s){
10+
if(s.length===0)return0;
11+
vardp=[1];
12+
s[0]==='0' ?dp[1]=0 :dp[1]=1;
13+
14+
for(vari=2;i<=s.length;i++){
15+
varprevTwo=parseInt(s.substring(i-2,i));
16+
dp[i]=0;
17+
if(s[i-1]!=='0')dp[i]=dp[i-1];
18+
if(prevTwo>=10&&prevTwo<=26)dp[i]+=dp[i-2];
19+
}
20+
21+
returndp[s.length];
22+
};

‎README.md‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -112,25 +112,30 @@
112112
*[86. Partition List](https://leetcode.com/problems/partition-list/) -[Solution](./Medium/86-partition-List.js)
113113
*[89. Gray Code](https://leetcode.com/problems/gray-code/) -[Solution](./Medium/89-grayCode.js)
114114
*[90. Subsets II](https://leetcode.com/problems/subsets-ii/) -[Solution](./Medium/90-subsetsII.js)
115+
*[91. Decode Ways](https://leetcode.com/problems/decode-ways/) -[Solution](./Medium/91-decodeways.js)
115116
*[92. Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/) -[Solution](./Medium/92-reverseLinkedListII.js)
116117
*[93. Restore IP Addresses](https://leetcode.com/problems/restore-ip-addresses/) -[Solution](./Medium/93-restoreIPAddresses.js)
117118
*[94. Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) -[Solution](./Medium/94-binaryTreeInorder.js)
118119
*[96. Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees/) -[Solution](./Medium/96-uniqueBinarySearchTrees.js)
119120
*[98. Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/) -[Solution](./Medium/98-validateBST.js)
120121
*[103. Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/) -[Solution](./Medium/103-BSTZigzagLevelTraversal.js)
121122
*[105. Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/) -[Solution](./Medium/105-constructBinaryTree.js)
123+
*[106. Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/) -[Solution](./Medium/106-constructBinaryTree.js)
122124
*[108. Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/) -[Solution](./Medium/108-convertSortedArraytoBST.js)
123125
*[109. Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) -[Solution](./Medium/109-convertSortedListToBST.js)
124126
*[113. Path Sum II](https://leetcode.com/problems/path-sum-ii/) -[Solution](./Medium/113-pathSumII.js)
125127
*[114. Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/) -[Solution](./Medium/114-flattenTree.js)
126128
*[116. Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node/) -[Solution](./Medium/116-PopulatingNextRightPointersinEachNode.js)
129+
*[120. Triangle](https://leetcode.com/problems/triangle/) -[Solution](./Medium/120-triangle.js)
127130
*[121. Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/) -[Solution](./Medium/121-bestTimeToBuySellStock.js)
128131
*[122. Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/) -[Solution](./Medium/122-bestTimeToBuySellStockII.js)
129132
*[129. Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers/) -[Solution](./Medium/129-sumRootToLeafNumbers.js)
130133
*[134. Gas Station](https://leetcode.com/problems/gas-station/) -[Solution](./Medium/134-gasStation.js)
131134
*[136. Single Number](https://leetcode.com/problems/single-number/) -[Solution](./Medium/136-singleNumber.js)
132135
*[141. Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/) -[Solution](./Medium/141-linkedListCycle.js)
133136
*[144. Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/) -[Solution](./Medium/144-binaryTreePreorder.js)
137+
*[151. Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) -[Solution](./Medium/151-reverseWordsInAString.js)
138+
*[152. Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/) -[Solution](./Medium/152-MaxProductSubarray.js)
134139
*[153.Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/) -[Solution](./Medium/153-findMinimumInRotatedSortedArray.js)
135140
*[162. Find Peak Element](https://leetcode.com/problems/find-peak-element/) -[Solution](./Medium/162-findPeakElement.js)
136141
*[199. Binary Tree Right Side View](https://leetcode.com/problems/binary-tree-right-side-view/) -[Solution](./Medium/199-binaryTreeRightSideView.js)

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp