leetcode

Overlapping intervals problems

5 files changed, 112 insertions(+), 9 deletions(-)

diff --git a/ Problems/0056.cpp b/ Problems/0056.cpp

@@ -0,0 +1,25 @@

class Solution {

typedef vector<int> interval;

public:

vector<interval> merge(vector<interval> &intervals) {

auto cmp = [](const interval &i1, const interval &i2) {

return i1[0] < i2[0];

};

sort(intervals.begin(), intervals.end(), cmp);

vector<interval> res;

int start = intervals[0][0], end = intervals[0][1];

for (auto &i : intervals) {

if (i[0] > end) {

res.push_back({start, end});

start = i[0];

}

end = max(end, i[1]);

}

if (res.empty() || res.back()[1] != end) res.push_back({start, end});

return res;

}

};

diff --git a/ Problems/0310.cpp b/ Problems/0310.cpp

@@ -0,0 +1,37 @@

class Solution {

public:

vector<int> findMinHeightTrees(int n, vector<vector<int>> &edges) {

if (n == 0) return {};

if (n == 1) return {0};

if (n == 2) return {0, 1};

vector<set<int>> adj(n);

vector<int> count(n);

for (auto &e : edges) {

adj[e[0]].insert(e[1]);

adj[e[1]].insert(e[0]);

count[e[0]]++;

count[e[1]]++;

}

queue<int> q;

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

if (count[i] == 1) q.push(i);

vector<int> res;

while (!q.empty()) {

res.clear();

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

int c = q.front();

q.pop();

res.push_back(c);

for (int n : adj[c]) {

if (--count[n] == 1) q.push(n);

}

}

}

return res;

}

};

diff --git a/ Problems/0435.cpp b/ Problems/0435.cpp

@@ -0,0 +1,20 @@

class Solution {

typedef vector<int> interval;

public:

int eraseOverlapIntervals(vector<interval> &intervals) {

auto cmp = [](const interval &i1, const interval &i2) {

return i1[1] < i2[1];

};

sort(intervals.begin(), intervals.end(), cmp);

int end = intervals[0][1], count = 1;

for (auto &i : intervals) {

if (i[0] >= end) {

end = i[1];

count++;

}

}

return intervals.size() - count;

}

};

diff --git a/ Problems/0452.cpp b/ Problems/0452.cpp

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

class Solution {

typedef vector<int> segment;

public:

int findMinArrowShots(vector<segment> &segments) {

auto cmp = [](const segment &a, const segment &b) { return a[1] < b[1]; };

sort(segments.begin(), segments.end(), cmp);

int res = 1, arrow = segments[0][1];

for (segment &s : segments) {

if (s[0] > arrow) {

res++;

arrow = s[1];

}

}

return res;

}

};

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

@@ -43,6 +43,7 @@ for solving problems. | 0049 | Medium | [Group Anagrams](Problems/0049.cpp) | | 0054 | Medium | [Spiral Matrix](Problems/0054.cpp) | | 0055 | Medium | [Jump Game](Problems/0055.cpp) |

| 0056 | Medium | [Merge Intervals](Problems/0056.cpp) |

| 0059 | Medium | [Spiral Matrix II](Problems/0059.cpp) | | 0061 | Medium | [Rotate List](Problems/0061.cpp) | | 0066 | Easy | [Plus One](Problems/0066.cpp) |

@@ -73,7 +74,7 @@ for solving problems. | 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) |

| 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) |

@@ -104,7 +105,7 @@ for solving problems. | 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) |

| 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 +114,7 @@ for solving problems. | 0287 | Medium | [Find the Duplicate Number](Problems/0287.cpp) | | 0290 | Easy | [Word Pattern](Problems/0290.cpp) | | 0295 | Hard | [Find Median from Data Stream](Problems/0295.cpp) |

| 0310 | Medium | [Minimum Height Trees](Problems/0310.cpp) |

| 0328 | Medium | [Odd Even Linked List](Problems/0328.cpp) | | 0338 | Easy | [Counting Bits](Problems/0338.cpp) | | 0344 | Easy | [Reverse String](Problems/0344.cpp) |

@@ -124,7 +126,7 @@ for solving problems. | 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) |

| 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) |

@@ -132,9 +134,11 @@ for solving problems. | 0429 | Medium | [N-ary Tree Level Order Traversal](Problems/0429.cpp) | | 0430 | Medium | [Flatten a Multilevel Doubly Linked list](Problems/0430.cpp) | | 0433 | Medium | [Minimum Genetic Mutation](Problems/0433.cpp) |

| 0435 | Medium | [Non-overlapping Intervals](Problems/0435.cpp) |

| 0445 | Medium | [Add Two Numbers II](Problems/0445.cpp) | | 0448 | Easy | [Find All Numbers Disappeared in an Array](Problems/0448.cpp) | | 0450 | Medium | [Delete Node in a BST](Problems/0450.cpp) |

| 0452 | Medium | [Minimum Number of Arrows to Burst Balloons](Problems/0452.cpp) |

| 0485 | Easy | [Max Consecutive Ones](Problems/0485.cpp) | | 0494 | Medium | [Target Sum](Problems/0494.cpp) | | 0496 | Medium | [Next Greater Element I](Problems/0496.cpp) |

@@ -145,7 +149,7 @@ for solving problems. | 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) |

| 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) |

@@ -161,7 +165,7 @@ for solving problems. | 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) |

| 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) |

@@ -232,10 +236,10 @@ for solving problems. | 1361 | Medium | [Validate Binary Tree Nodes](Problems/1361.cpp) | | 1367 | Medium | [Linked List in Binary Tree ](Problems/1367.cpp) | | 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) |

| 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) |

| 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) |

| 1462 | Medium | [Course Schedule IV](Problems/1462.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) |

@@ -282,7 +286,7 @@ for solving problems. | 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) |

| 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) |