leetcode

Remove DNF section - README.md * I've finished all DNF problems * Template section is now at the top

9 files changed, 177 insertions(+), 113 deletions(-)

diff --git a/ Problems/0129.cpp b/ Problems/0129.cpp

@@ -0,0 +1,26 @@

class Solution {

public:

int sumNumbers(TreeNode *root) {

if (!root) return 0;

int sum = 0, res = 0;

stack<pair<TreeNode *, int>> st;

while (true) {

while (root) {

sum *= 10;

sum += root->val;

if (root->right)

st.push({root->right, sum});

else if (!root->left)

res += sum;

root = root->left;

}

if (st.empty()) break;

root = st.top().first;

sum = st.top().second;

st.pop();

}

return res;

}

};

diff --git a/ Problems/0143.cpp b/ Problems/0143.cpp

@@ -0,0 +1,18 @@

class Solution {

public:

int longestSubarray(vector<int> &nums, int limit) {

deque<int> maxd, mind;

int i = 0, j;

for (j = 0; j < nums.size(); ++j) {

while (!maxd.empty() && nums[j] > maxd.back()) maxd.pop_back();

while (!mind.empty() && nums[j] < mind.back()) mind.pop_back();

maxd.push_back(nums[j]), mind.push_back(nums[j]);

if (maxd.front() - mind.front() > limit) {

if (maxd.front() == nums[i]) maxd.pop_front();

if (mind.front() == nums[i]) mind.pop_front();

i++;

}

}

return j - i;

}

};

diff --git a/ Problems/0239.cpp b/ Problems/0239.cpp

@@ -0,0 +1,17 @@

class Solution {

public:

vector<int> maxSlidingWindow(vector<int> &nums, int k) {

int n = nums.size();

vector<int> res;

deque<int> q;

res.reserve(n - k + 1);

for (int i = 0; i < n; i++) {

while (!q.empty() && q.front() < i - k + 1) q.pop_front();

while (!q.empty() && nums[q.back()] < nums[i]) q.pop_back();

q.push_back(i);

if (i >= k - 1) res.push_back(nums[q.front()]);

}

return res;

}

};

diff --git a/ Problems/0402.cpp b/ Problems/0402.cpp

@@ -1,26 +1,28 @@ class Solution {

public:

string removeKdigits(string num, int k) {

stack<char> st;

for (char c : num) {

while (k && !st.empty() && c < st.top()) {

k--;

st.pop();

}

if (st.empty() && c == '0') continue;

st.push(c);

}

string res = "";

class Solution {

public:

string removeKdigits(string num, int k) {

if (num.length() <= k) return "0";

if (k == 0) return num;

while (!st.empty() && k--) st.pop();

string res = "";

stack<char> s;

while (!st.empty()) {

res = st.top() + res;

st.pop();

}

s.push(num[0]);

for (int i = 1; i < num.length(); ++i) {

while (k > 0 && !s.empty() && num[i] < s.top()) {

--k;

s.pop();

}

s.push(num[i]);

if (s.size() == 1 && num[i] == '0') s.pop();

}

while (k && !s.empty()) --k, s.pop();

if (res == "") return "0";

while (!s.empty()) res.push_back(s.top()), s.pop();

return res;

}

};

reverse(res.begin(), res.end());

return res.size() ? res : "0";

}

};

diff --git a/ Problems/0542.cpp b/ Problems/0542.cpp

@@ -1,52 +1,45 @@ class Solution {

queue<pair<int, int>> q;

int m, n;

typedef vector<vector<int>> vvi;

vector<pair<int, int>> offset = {

{-1, 0},

{ 1, 0},

{ 0, -1},

{ 0, 1}

};

int valid(int sr, int sc) { return sr >= 0 && sr < m && sc >= 0 && sc < n; }

void add(vvi &mat, int sr, int sc) {

cout << sr << " " << sc << " valid is: " << valid(sr, sc) << endl;

if (valid(sr, sc) && mat[sr][sc] != 0) q.push(make_pair(sr, sc));

}

void ff(vvi &mat, vvi &res, int sr, int sc) {

q.push(make_pair(sr, sc));

for (int lvl = 0; !q.empty(); lvl++) {

for (int t = q.size(); t > 0; t--) {

int sr = q.front().first;

int sc = q.front().second;

cout << "lvl" << lvl << ": " << sr << " " << sc << endl;

q.pop();

if (!res[sr][sc] || res[sr][sc] > lvl)

res[sr][sc] = lvl;

else

continue;

cout << "adding" << endl;

add(mat, sr + 1, sc);

add(mat, sr - 1, sc);

add(mat, sr, sc + 1);

add(mat, sr, sc - 1);

}

}

cout << "end FF" << endl;

}

public:

vector<vector<int>> updateMatrix(vvi &mat) {

vector<vector<int>> updateMatrix(vector<vector<int>> &mat) {

m = mat.size(); n = mat[0].size();

cout << m << " " << n << endl;

vector<vector<int>> res(m, vector<int>(n, INT_MAX));

queue<pair<int, int>> q;

vvi res(m, vector<int>(n, 0));

for (int i = 0; i < m; i++) {

for (int j = 0; j < n; j++) {

if (mat[i][j] == 0) {

res[i][j] = 0;

q.push({i, j});

}

}

}

for (int i = 0; i < m; i++)

for (int j = 0; j < n; j++)

if (mat[i][j] == 0) ff(mat, res, i, j);

while (!q.empty()) {

auto [sr, sc] = q.front();

q.pop();

for (auto &p : offset) {

int nsr = sr + p.first;

int nsc = sc + p.second;

if (valid(nsr, nsc)) {

if (res[nsr][nsc] > res[sr][sc] + 1) {

res[nsr][nsc] = res[sr][sc] + 1;

q.push({nsr, nsc});

}

}

}

}

return res; }

diff --git a/ Problems/0662.cpp b/ Problems/0662.cpp

@@ -1,25 +1,25 @@ class Solution { public: int widthOfBinaryTree(TreeNode *root) {

int maxi = 0;

queue<TreeNode *> q;

q.push(root);

for (int lvl = 0; !q.empty(); lvl++) {

int first = -1, last = -1;

for (int t = q.size(); t > 0; t--) {

TreeNode *root = q.front();

if (root == NULL) return 0;

queue<pair<TreeNode *, int>> q;

int res = 1;

q.push({root, 0});

while (!q.empty()) {

int start = q.front().second, end = q.back().second;

res = max(res, end - start + 1);

for (int k = q.size(); k > 0; k--) {

pair<TreeNode *, int> p = q.front();

q.pop();

if (root) {

if (first == -1) first = t;

last = t;

}

if (!root) continue;

int idx = p.second - start;

q.push(root->left);

q.push(root->right);

if (p.first->left) q.push({p.first->left, 2ll * idx + 1});

if (p.first->right) q.push({p.first->right, 2ll * idx + 2});

}

maxi = max(maxi, first - last);

}

return maxi;

return res;

} };

diff --git a/ Problems/1425.cpp b/ Problems/1425.cpp

@@ -0,0 +1,15 @@

class Solution {

public:

int constrainedSubsetSum(vector<int> &nums, int k) {

deque<int> q;

int res = nums[0];

for (int i = 0; i < nums.size(); ++i) {

nums[i] += !q.empty() ? q.front() : 0;

res = max(res, nums[i]);

while (!q.empty() && nums[i] > q.back()) q.pop_back();

if (nums[i] > 0) q.push_back(nums[i]);

if (i >= k && !q.empty() && q.front() == nums[i - k]) q.pop_front();

}

return res;

}

};

diff --git a/ Problems/2461.cpp b/ Problems/2461.cpp

@@ -1,26 +1,18 @@ class Solution { public: long long maximumSubarraySum(vector<int> &nums, int k) {

long long maxi = LLONG_MIN;

unordered_set<int> us;

int i = 0;

long long sum = 0ll;

for (int j = 0; j <= size(nums);) {

while (us.find(nums[j]) != us.end()) {

sum -= nums[i];

us.erase(nums[i++]);

}

if (j - i < k) {

sum += nums[j];

us.insert(nums[j++]);

}

if (j > size(nums)) break;

if (j - i == k) {

maxi = max(sum, maxi);

sum -= nums[i];

us.erase(nums[i++]);

}

unordered_map<int, int> mp;

long maxi = 0, sum = 0;

for (int i = 0; i < nums.size(); i++) {

sum += nums[i];

mp[nums[i]]++;

if (i < k - 1) continue;

if (mp.size() == k) maxi = max(maxi, sum);

int &tmp = nums[i - k + 1];

sum -= tmp;

if (--mp[tmp] == 0) mp.erase(tmp);

}

return maxi == LLONG_MIN ? 0 : maxi;

return maxi;

} };

diff --git a/ README.md b/ README.md

@@ -10,6 +10,15 @@ update this list periodically as I do more problems. I hope it will be helpful to some of you if you get stuck on a specific problem. Feel free to contact me if you have any questions.

## Templates

I have accumulated a list of most commonly used algorithms to serve as a base

for solving problems.

* [Union Find](Templates/Union_Find.cpp)

* [MST from edge vector](Templates/MST_vector.cpp)

* [MST from edge priority queue](Templates/MST_pq.cpp)

## Problems | Number | Difficulty | Solution |

@@ -64,6 +73,7 @@ if you have any questions. | 0122 | Medium | [Best Time to Buy and Sell Stock II](Problems/0122.cpp) | | 0124 | Hard | [Binary Tree Maximum Path Sum](Problems/0124.cpp) | | 0125 | Easy | [Valid Palindrome](Problems/0125.cpp) |

| 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) |

| 0133 | Medium | [Clone Graph](Problems/0133.cpp) | | 0138 | Medium | [Copy List with Random Pointer](Problems/0138.cpp) | | 0141 | Easy | [Linked List Cycle](Problems/0141.cpp) |

@@ -94,6 +104,7 @@ if you have any questions. | 0236 | Medium | [Lowest Common Ancestor of a Binary Tree](Problems/0236.cpp) | | 0237 | Medium | [Delete Node in a Linked List](Problems/0237.cpp) | | 0238 | Medium | [Product of Array Except Self](Problems/0238.cpp) |

| 0239 | Hard | [Sliding Window Maximum](Problems/0239.cpp) |

| 0242 | Easy | [Valid Anagram](Problems/0242.cpp) | | 0257 | Easy | [Binary Tree Paths](Problems/0257.cpp) | | 0263 | Easy | [Ugly Number](Problems/0263.cpp) |

@@ -113,6 +124,7 @@ if you have any questions. | 0392 | Easy | [Is Subsequence](Problems/0392.cpp) | | 0394 | Medium | [Decode String](Problems/0394.cpp) | | 0399 | Medium | [Evaluate Division](Problems/0399.cpp) |

| 0402 | Medium | [Remove K Digits](Problems/0402.cpp) |

| 0404 | Easy | [Sum of Left Leaves](Problems/0404.cpp) | | 0412 | Easy | [Fizz Buzz](Problems/0412.cpp) | | 0414 | Easy | [Third Maximum Number](Problems/0414.cpp) |

@@ -133,6 +145,7 @@ if you have any questions. | 0520 | Easy | [Detect Capital](Problems/0520.cpp) | | 0530 | Easy | [Minimum Absolute Difference in BST](Problems/0530.cpp) | | 0538 | Medium | [Convert BST to Greater Tree](Problems/0538.cpp) |

| 0542 | Medium | [01 Matrix](Problems/0542.cpp) |

| 0543 | Easy | [Diameter of Binary Tree](Problems/0543.cpp) | | 0547 | Medium | [Number of Provinces](Problems/0547.cpp) | | 0556 | Medium | [Next Greater Element III](Problems/0556.cpp) |

@@ -148,6 +161,7 @@ if you have any questions. | 0637 | Easy | [Average of Levels in Binary Tree](Problems/0637.cpp) | | 0653 | Easy | [Two Sum IV - Input is a BST](Problems/0653.cpp) | | 0654 | Medium | [Maximum Binary Tree](Problems/0654.cpp) |

| 0662 | Medium | [Maximum Width of Binary Tree](Problems/0662.cpp) |

| 0669 | Medium | [Trim a Binary Search Tree](Problems/0669.cpp) | | 0671 | Easy | [Second Minimum Node In a Binary Tree](Problems/0671.cpp) | | 0684 | Medium | [Redundant Connection](Problems/0684.cpp) |

@@ -178,6 +192,7 @@ if you have any questions. | 0933 | Easy | [Number of Recent Calls](Problems/0933.cpp) | | 0938 | Easy | [Range Sum of BST](Problems/0938.cpp) | | 0941 | Easy | [Valid Mountain Array](Problems/0941.cpp) |

| 0944 | Easy | [Delete Columns to Make Sorted](Problems/0944.cpp) |

| 0947 | Medium | [Most Stones Removed with Same Row or Column](Problems/0947.cpp) | | 0950 | Medium | [Reveal Cards In Increasing Order](Problems/0950.cpp) | | 0959 | Medium | [Regions Cut By Slashes](Problems/0959.cpp) |

@@ -218,9 +233,12 @@ if you have any questions. | 1373 | Hard | [Maximum Sum BST in Binary Tree](Problems/1373.cpp) | | 1379 | Easy | [Find a Corresponding Node of a Binary Tree in a Clone of That Tree](Problems/1379.cpp) | | 1382 | Medium | [Balance a Binary Search Tree](Problems/1382.cpp) |

| 1425 | Hard | [Constrained Subsequence Sum](Problems/1425.cpp) |

| 1438 | Medium | [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](Problems/0143.cpp) |

| 1466 | Medium | [Reorder Routes to Make All Paths Lead to the City Zero](Problems/1466.cpp) | | 1472 | Medium | [Design Browser History ](Problems/1472.cpp) | | 1480 | Easy | [Running Sum of 1d Array](Problems/1480.cpp) |

| 1489 | Hard | [Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree](Problems/1489.cpp) |

| 1514 | Medium | [Path with Maximum Probability](Problems/1514.cpp) | | 1544 | Easy | [Make The String Great](Problems/1544.cpp) | | 1557 | Medium | [Minimum Number of Vertices to Reach All Nodes](Problems/1557.cpp) |

@@ -260,27 +278,10 @@ if you have any questions. | 2368 | Medium | [Reachable Nodes With Restrictions](Problems/2368.cpp) | | 2374 | Medium | [Node With Highest Edge Score](Problems/2374.cpp) | | 2390 | Medium | [Removing Stars From a String](Problems/2390.cpp) |

| 2461 | Medium | [Maximum Sum of Distinct Subarrays With Length K](Problems/2461.cpp) |

| 2465 | Easy | [Number of Distinct Averages](Problems/2465.cpp) | | 2466 | Medium | [Count Ways To Build Good Strings](Problems/2466.cpp) | | 2467 | Medium | [Most Profitable Path in a Tree](Problems/2467.cpp) | | 2477 | Medium | [Minimum Fuel Cost to Report to the Capital](Problems/2477.cpp) | | 2492 | Medium | [Minimum Score of a Path Between Two Cities](Problems/2492.cpp) |

| 0944 | Easy | [Delete Columns to Make Sorted](Problems/0944.cpp) |

| 1489 | Hard | [Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree](Problems/1489.cpp) |

## Templates

* [Union Find](Templates/Union_Find.cpp)

* [MST from edge vector](Templates/MST_vector.cpp)

* [MST from edge priority queue](Templates/MST_pq.cpp)

## DNF

| Number | Difficulty | Solution |

|:------:|:----------:|-------------------------------------------------------------------------------------------------|

| 0402 | Medium | [Remove K Digits](Problems/0402.cpp) |

| 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) |

| 0542 | Medium | [01 Matrix](Problems/0542.cpp) |

| 0662 | Medium | [Maximum Width of Binary Tree](Problems/0662.cpp) |

| 1438 | Medium | [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](Problems/0143.cpp) |

| 2461 | Medium | [Maximum Sum of Distinct Subarrays With Length K](Problems/2461.cpp) |