Add Q218, Q219, Q220

Author: theFool32

218_TheSkylineProblem/TheSkylineProblem.cc

@@ -0,0 +1,27 @@
+//https://discuss.leetcode.com/topic/25794/17-line-o-n-log-n-time-o-n-space-c-accepted-easy-solution-w-explanations
+class Solution {
+public:
+    vector<pair<int, int>> getSkyline(vector<vector<int>>& buildings) {
+        multimap<int, int> coords;
+        for (auto&& building : buildings) {
+            coords.emplace(building[0], building[2]);
+            coords.emplace(building[1], -building[2]);
+        }
+
+        multiset<int> heights = {0};
+        map<int, int> corners;
+        for (auto&& p : coords) {
+            if (p.second > 0) {
+                heights.insert(p.second);
+            } else {
+                heights.erase(heights.find(-p.second));
+            }
+            corners[p.first] = *heights.rbegin();
+        }
+        auto eq2nd = [](pair<int, int> l, pair<int, int> r){ return l.second == r.second;  };
+		vector<pair<int, int>> results;
+		unique_copy(corners.begin(), corners.end(), back_insert_iterator<vector<pair<int, int>>>(results), eq2nd);
+
+        return results;
+    }
+};

219_ContainsDuplicate2/ContainsDuplicate2.cc

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    bool containsNearbyDuplicate(vector<int>& nums, int k) {
+        map<int, int> m;
+        for (int i = 0; i < nums.size(); ++i) {
+            if (m.find(nums[i]) != m.end()) {
+                if (i - m[nums[i]] <= k) return true;
+                m[nums[i]] = i;
+            } else {
+                m[nums[i]] = i;
+            }
+        }
+        return false;
+    }
+};

220_ContainsDuplicate3/ContainsDuplicate3.cc

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    bool containsNearbyAlmostDuplicate(vector<int>& nums, int k, int t) {
+        if (t < 0) return false;
+        unordered_map<long, long> m;
+#define BIN(i, t) (i < 0 ? (i+1)/(t+1)-1 : i/(t+1))
+        for (int i = 0; i < nums.size(); ++i) {
+            int b = BIN(nums[i], t);
+            if (m.find(b) != m.end()) {
+                return true;
+            }
+            if (m.find(b-1) != m.end() && abs(nums[i] - m[b-1]) <= t) {
+                return true;
+            }
+            if (m.find(b+1) != m.end() && abs(nums[i] - m[b+1]) <= t) {
+                return true;
+            }
+            m[b] = nums[i];
+
+            if (i >= k) {
+                m.erase(BIN(nums[i-k], t));
+            }
+        }
+        return false;
+    }
+};