leetcode

Random problems, and orphaned file removal

7 files changed, 134 insertions(+), 57 deletions(-)

diff --git a/ Problems/0084.cpp b/ Problems/0084.cpp

@@ -0,0 +1,31 @@

class Solution {

public:

int largestRectangleArea(vector<int> &heights) {

int n = heights.size();

vector<int> left(n), right(n);

stack<int> st;

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

left[i] = i;

while (!st.empty() && heights[st.top()] >= heights[i]) {

left[i] = left[st.top()];

st.pop();

};

st.push(i);

}

for (int i = n - 1; i >= 0; i--) {

right[i] = i;

while (!st.empty() && heights[st.top()] >= heights[i]) {

right[i] = right[st.top()];

st.pop();

};

st.push(i);

}

int res = 0;

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

res = max(res, (right[i] - left[i] + 1) * heights[i]);

return res;

}

};

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

@@ -1,18 +1,42 @@ class Solution {

ListNode *reverseList(ListNode *head) {

ListNode *p, *q, *r;

p = head, q = nullptr;

while (p) {

r = q;

q = p;

p = p->next;

q->next = r;

}

return q;

}

ListNode *bmiddleNode(ListNode *head) {

ListNode *fast, *slow;

fast = slow = head;

while (fast->next && fast->next->next) {

fast = fast->next->next;

slow = slow->next;

}

return slow;

}

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++;

}

void reorderList(ListNode *head) {

ListNode *bmid = bmiddleNode(head);

ListNode *rev = reverseList(bmid->next);

bmid->next = nullptr;

ListNode top, *tmp = &top, *a, *b, *an;

for (a = head, b = rev; b; b = b->next, a = an) {

an = a->next;

tmp = tmp->next = a;

tmp = tmp->next = b;

}

return j - i;

if (a) tmp = tmp->next = a;

tmp->next = nullptr;

} };

diff --git a/ Problems/0853.cpp b/ Problems/0853.cpp

@@ -0,0 +1,44 @@

class Solution {

public:

int carFleet(int target, vector<int> &position, vector<int> &speed) {

int n = position.size();

if (!n) return 0;

vector<pair<int, double>> vp(n + 1);

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

vp[i] = {position[i], (double)(target - position[i]) / speed[i]};

sort(vp.rbegin(), vp.rend());

int res = 0;

double ct = 0;

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

auto [_, time] = vp[i];

if (time > ct) {

res++;

ct = time;

}

}

return res;

}

};

// Using map for the heavy lifting

class Solution {

public:

int carFleet(int target, vector<int> &position, vector<int> &speed) {

map<int, double> mp;

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

mp[-position[i]] = (double)(target - position[i]) / speed[i];

int res = 0;

double ct = 0;

for (auto [_, time] : mp) {

if (time > ct) {

res++;

ct = time;

}

}

return res;

}

};

diff --git a/ Problems/102.cpp b/ Problems/102.cpp

@@ -1,22 +0,0 @@

class Solution {

public:

vector<vector<int>> levelOrder(TreeNode *root) {

if (!root) return {};

vector<vector<int>> res;

queue<TreeNode *> q;

q.push(root);

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

res.push_back(vector<int>());

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

TreeNode *root = q.front();

q.pop();

res[lvl].push_back(root->val);

if (root->left) q.push(root->left);

if (root->right) q.push(root->right);

}

}

return res;

}

};

diff --git a/ Problems/1438.cpp b/ Problems/1438.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/841.cpp b/ Problems/841.cpp

@@ -1,21 +0,0 @@

class Solution {

public:

bool canVisitAllRooms(vector<vector<int>> &rooms) {

unordered_set<int> us;

queue<int> q;

q.push(0);

us.insert(0);

while (!q.empty()) {

int room = q.front();

q.pop();

for (int key : rooms[room]) {

if (!us.count(key)) {

us.insert(key);

q.push(key);

}

}

}

return us.size() == rooms.size();

}

};

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

@@ -58,6 +58,7 @@ for solving problems. | 0067 | Easy | [Add Binary](Problems/0067.cpp) | | 0070 | Easy | [Climbing Stairs](Problems/0070.cpp) | | 0083 | Easy | [Remove Duplicates from Sorted List](Problems/0083.cpp) |

| 0084 | Hard | [Largest Rectangle in Histogram](Problems/0084.cpp) |

| 0088 | Easy | [Merge Sorted Array](Problems/0088.cpp) | | 0093 | Medium | [Restore IP Addresses](Problems/0093.cpp) | | 0094 | Easy | [Binary Tree Inorder Traversal](Problems/0094.cpp) |

@@ -92,6 +93,7 @@ for solving problems. | 0138 | Medium | [Copy List with Random Pointer](Problems/0138.cpp) | | 0141 | Easy | [Linked List Cycle](Problems/0141.cpp) | | 0142 | Medium | [Linked List Cycle II](Problems/0142.cpp) |

| 0143 | Medium | [Reorder List](Problems/0143.cpp) |

| 0144 | Medium | [Binary Tree Preorder Traversal](Problems/0144.cpp) | | 0145 | Easy | [Binary Tree Postorder Traversal](Problems/0145.cpp) | | 0149 | Hard | [Max Points on a Line](Problems/0149.cpp) |

@@ -216,6 +218,7 @@ for solving problems. | 0841 | Medium | [Keys and Rooms](Problems/0841.cpp) | | 0844 | Easy | [Backspace String Compare](Problems/0844.cpp) | | 0851 | Medium | [Loud and Rich](Problems/0851.cpp) |

| 0853 | Medium | [Car Fleet](Problems/0853.cpp) |

| 0872 | Easy | [Leaf-Similar Trees](Problems/0872.cpp) | | 0876 | Easy | [Middle of the Linked List](Problems/0876.cpp) | | 0884 | Easy | [Uncommon Words from Two Sentences](Problems/0884.cpp) |

@@ -276,7 +279,7 @@ for solving problems. | 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) |

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

| 1443 | Medium | [Minimum Time to Collect All Apples in a Tree](Problems/1443.cpp) | | 1462 | Medium | [Course Schedule IV](Problems/1462.cpp) | | 1466 | Medium | [Reorder Routes to Make All Paths Lead to the City Zero](Problems/1466.cpp) |