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Commit38ea709

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Merge branch 'neetcode-gh:main' into ginger
2 parents5c28166 +c440eb2 commit38ea709

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75 files changed

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-63
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75 files changed

+1764
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lines changed

‎README.md

Lines changed: 20 additions & 20 deletions
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classSolution {
2+
public:
3+
stringremoveStars(string s) {
4+
stack<char> stk;
5+
for(int i=0;i<s.size();i++){
6+
if(s[i]=='*'){
7+
stk.pop();
8+
}else stk.push(s[i]);
9+
}
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string res ="";
11+
while(!stk.empty()){
12+
res += stk.top();
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stk.pop();
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}
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reverse(res.begin(), res.end());
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return res;
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}
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};

‎csharp/0187-repeated-dna-sequences.cs

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publicclassSolution
2+
{
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publicIList<string>FindRepeatedDnaSequences(strings)
4+
{
5+
varseen=newHashSet<string>();
6+
varresult=newHashSet<string>();
7+
8+
for(vari=0;i<s.Length-9;i++)
9+
{
10+
varcur=s.Substring(i,10);
11+
if(seen.Contains(cur))
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result.Add(cur);
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seen.Add(cur);
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}
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returnresult.ToList();
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}
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}

‎csharp/0344-reverse-string.cs

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publicclassSolution
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{
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publicvoidReverseString(char[]s)
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{
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varh=s.Length/2;
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for(inti=0;i<h;i++)
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{
8+
vartemp=s[i];
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s[i]=s[s.Length-i-1];
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s[s.Length-i-1]=temp;
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}
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}
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}
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publicclassSolution
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{
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publicboolCheckSubarraySum(int[]nums,intk)
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{
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varremainder=newDictionary<int,int>();
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remainder.Add(0,-1);
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vartotal=0;
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for(vari=0;i<nums.Length;i++)
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{
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total+=nums[i];
11+
varr=total%k;
12+
if(!remainder.ContainsKey(r))
13+
remainder.Add(r,i);
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elseif(i-remainder[r]>1)
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returntrue;
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}
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returnfalse;
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}
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}
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publicclassSolution
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{
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publicstringMergeAlternately(stringword1,stringword2)
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{
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varresult=string.Empty;
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varfirstPointer=0;
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varsecondPointer=0;
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while(firstPointer<word1.Length||secondPointer<word2.Length)
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{
10+
if(firstPointer<word1.Length)
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result+=word1[firstPointer++];
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13+
if(secondPointer<word2.Length)
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result+=word2[secondPointer++];
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}
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returnresult;
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}
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}
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classSolution {
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intminCostClimbingStairs(List<int> cost) {
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for (int i= cost.length-3; i>=0; i--) {
4+
cost[i]+=min(cost[i+1], cost[i+2]);
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}
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7+
returnmin(cost[0], cost[1]);
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}
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}
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classSolution {
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publicintremoveDuplicates(int[]nums) {
3+
intk =0;
4+
for (intnum:nums) {
5+
if (k <2 ||nums[k-2] !=num) {
6+
nums[k++] =num;
7+
}
8+
}
9+
returnk;
10+
}
11+
}

‎java/0110-balanced-binary-tree.java

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Original file line numberDiff line numberDiff line change
@@ -25,3 +25,32 @@ public static boolean isBalanced(TreeNode root) {
2525
returndfs(root).getKey();
2626
}
2727
}
28+
29+
// Solution using the bottom up approach
30+
// TC and SC is On
31+
32+
classSolution {
33+
34+
publicintheight(TreeNoderoot){
35+
if(root ==null){
36+
return0;
37+
}
38+
39+
intlh =height(root.left);
40+
intrh =height(root.right);
41+
42+
return1 +Math.max(lh,rh);
43+
}
44+
45+
publicbooleanisBalanced(TreeNoderoot) {
46+
47+
if(root ==null){
48+
returntrue;
49+
}
50+
51+
intlh =height(root.left);
52+
intrh =height(root.right);
53+
54+
returnMath.abs(lh -rh) <=1 &&isBalanced(root.left) &&isBalanced(root.right);
55+
}
56+
}
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classSolution {
2+
publicNodeconnect(Noderoot) {
3+
Nodecurrent =root;
4+
Nodenext =root ==null ?null :root.left;
5+
6+
while (current !=null &&next !=null) {
7+
current.left.next =current.right;
8+
9+
if (current.next !=null) {
10+
current.right.next =current.next.left;
11+
}
12+
13+
current =current.next;
14+
15+
if (current ==null) {
16+
current =next;
17+
next =current.left;
18+
}
19+
}
20+
21+
returnroot;
22+
}
23+
}

‎java/0147-insertion-sort-list.java

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@@ -0,0 +1,27 @@
1+
classSolution {
2+
publicListNodeinsertionSortList(ListNodehead) {
3+
ListNodedummy =newListNode(0,head);
4+
5+
ListNodeprev =head;
6+
ListNodecur =head.next;
7+
while (cur !=null) {
8+
if (prev.val <=cur.val) {
9+
prev =cur;
10+
cur =cur.next;
11+
}else {
12+
ListNodeelem =dummy;
13+
while (elem.next.val <cur.val) {
14+
elem =elem.next;
15+
}
16+
17+
prev.next =cur.next;
18+
cur.next =elem.next;
19+
elem.next =cur;
20+
21+
cur =prev.next;
22+
}
23+
}
24+
25+
returndummy.next;
26+
}
27+
}

‎java/0162-find-peak-element.java

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classSolution {
2+
publicintfindPeakElement(int[]nums) {
3+
intl =0,r =nums.length-1;
4+
while(l<=r){
5+
intm =l + (r-l)/2;
6+
intleft = (m-1==-1)?Integer.MIN_VALUE:nums[m-1];
7+
intright = (m+1==nums.length)?Integer.MIN_VALUE:nums[m+1];
8+
if(nums[m]>left &&nums[m]>right)returnm;
9+
elseif(nums[m]<left)r=m-1;
10+
elsel =m+1;
11+
}
12+
return0;
13+
}
14+
}

‎java/0226-invert-binary-tree.java

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@@ -4,7 +4,6 @@ public TreeNode invertTree(TreeNode root) {
44
if (root ==null)returnnull;
55
TreeNodenode =newTreeNode(root.val);
66
node.right =invertTree(root.left);
7-
node.val =root.val;
87
node.left =invertTree(root.right);
98
returnnode;
109
}
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classNumMatrix {
2+
int[][]preSum;
3+
4+
publicNumMatrix(int[][]matrix) {
5+
intm =matrix.length;
6+
intn =matrix[0].length;
7+
preSum =newint[m +1][n +1];
8+
9+
for (inti =0;i <m;i++) {
10+
for (intj =0;j <n;j++) {
11+
preSum[i +1][j +1] =preSum[i +1][j] +preSum[i][j +1] -preSum[i][j] +matrix[i][j];
12+
}
13+
}
14+
}
15+
16+
publicintsumRegion(introw1,intcol1,introw2,intcol2) {
17+
returnpreSum[row2 +1][col2 +1] -preSum[row2 +1][col1] -preSum[row1][col2 +1] +preSum[row1][col1];
18+
}
19+
}
20+
21+
/**
22+
* Your NumMatrix object will be instantiated and called as such:
23+
* NumMatrix obj = new NumMatrix(matrix);
24+
* int param_1 = obj.sumRegion(row1,col1,row2,col2);
25+
*/
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publicclassSolution {
2+
publicintnumberOfArithmeticSlices(int[]nums) {
3+
intres =0;
4+
intn =nums.length;
5+
6+
Map<Long,Integer>[]dp =newHashMap[n];
7+
for (inti =0;i <n;i++) {
8+
dp[i] =newHashMap<>();
9+
}
10+
11+
for (inti =0;i <n;i++) {
12+
for (intj =0;j <i;j++) {
13+
longdiff = (long)nums[i] - (long)nums[j];
14+
dp[i].put(diff,dp[i].getOrDefault(diff,0) +1 +dp[j].getOrDefault(diff,0));
15+
res +=dp[j].getOrDefault(diff,0);
16+
}
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}
18+
19+
returnres;
20+
}
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}

‎java/0455-assign-cookies.java

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1+
classSolution {
2+
publicintfindContentChildren(int[]g,int[]s) {
3+
Arrays.sort(g);
4+
Arrays.sort(s);
5+
6+
inti =0,j =0;
7+
while(i <g.length){
8+
while(j <s.length &&g[i] >s[j])
9+
j +=1;
10+
if(j ==s.length)
11+
break;
12+
i +=1;
13+
j +=1;
14+
}
15+
returni;
16+
}
17+
}

‎java/0661-image-smoother.java

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@@ -0,0 +1,52 @@
1+
classSolution {
2+
publicint[][]imageSmoother(int[][]img) {
3+
intROWS =img.length,COLS =img[0].length;
4+
int[][]res =newint[ROWS][COLS];
5+
6+
for(intr =0;r <ROWS;r++){
7+
for(intc =0;c <COLS;c++){
8+
inttotal =0,cnt =0;
9+
for(inti =r -1;i <r +2;i++){
10+
for(intj =c -1;j <c +2;j++){
11+
if(i <0 ||i ==ROWS ||j <0 ||j ==COLS)
12+
continue;
13+
total +=img[i][j];
14+
cnt +=1;
15+
}
16+
}
17+
res[r][c] =total /cnt;
18+
}
19+
}
20+
returnres;
21+
}
22+
}
23+
24+
// Optimal Solution
25+
26+
classSolution {
27+
publicint[][]imageSmoother(int[][]img) {
28+
intROWS =img.length,COLS =img[0].length;
29+
30+
for(intr =0;r <ROWS;r++){
31+
for(intc =0;c <COLS;c++){
32+
inttotal =0,cnt =0;
33+
34+
for(inti =r -1;i <r +2;i++){
35+
for(intj =c -1;j <c +2;j++){
36+
if(i <0 ||i ==ROWS ||j <0 ||j ==COLS)
37+
continue;
38+
total +=img[i][j] %256;
39+
cnt +=1;
40+
}
41+
}
42+
img[r][c] =img[r][c] ^ (total /cnt) <<8;
43+
}
44+
}
45+
for(intr =0;r <ROWS;r++){
46+
for(intc =0;c <COLS;c++){
47+
img[r][c] =img[r][c] >>8;
48+
}
49+
}
50+
returnimg;
51+
}
52+
}

‎java/0704-binary-search.java

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,9 @@ public int search(int[] nums, int target) {
55
intj =nums.length -1;
66

77
while (i <=j) {
8-
intmid = (i +j) /2;
8+
// mid is calculated this way to prevent integer overflow.
9+
// See: https://blog.research.google/2006/06/extra-extra-read-all-about-it-nearly.html
10+
intmid =i + (j -i) /2;
911

1012
if (nums[mid] ==target)returnmid;elseif (
1113
nums[mid] <target

‎java/0872-leaf-similar-trees.java

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1+
classSolution {
2+
publicbooleanleafSimilar(TreeNoderoot1,TreeNoderoot2) {
3+
ArrayList<Integer>ls1 =newArrayList<>();
4+
ArrayList<Integer>ls2 =newArrayList<>();
5+
tree(root1,ls1);
6+
tree(root2,ls2);
7+
returnls1.equals(ls2);
8+
}
9+
privatevoidtree(TreeNoderoot,List<Integer>ls){
10+
if(root ==null)
11+
return;
12+
if(root.left ==null &&root.right ==null)
13+
ls.add(root.val);
14+
tree(root.left,ls);
15+
tree(root.right,ls);
16+
}
17+
}

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