区间离散化解法（低效 120ms）

Author: zouwx2cs

solution/0218.The Skyline Problem

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+// 区间离散化解法（低效 120ms）
+class Solution {
+public:
+    vector<pair<int, int>> getSkyline(vector<vector<int>>& buildings) {
+        set<int> poss ;
+        map<int, int> m ;
+        for (auto v: buildings)
+        {
+            poss.insert(v[0]) ;
+            poss.insert(v[1]) ;
+        }
+        
+        int i = 0 ;
+        for (int pos: poss)
+            m.insert(pair<int, int>(pos, i++)) ;
+        
+        vector<int> highs(m.size(), 0) ;
+        for (auto v: buildings)
+        {
+            const int b = m[v[0]], e = m[v[1]] ;
+            for (int i = b; i < e; ++i)
+                highs[i] = max(highs[i], v[2]) ;
+        }
+        
+        vector<pair<int, int>> res ;
+        vector<int> mm(poss.begin(), poss.end()) ;
+        for (int i = 0; i < highs.size(); ++i)
+        {
+            if (highs[i] != highs[i+1])
+                res.push_back(pair<int, int>(mm[i], highs[i])) ;
+            else
+            {
+                const int start = i ;
+                res.push_back(pair<int, int>(mm[start], highs[i])) ;
+                while (highs[i] == highs[i+1])
+                    ++i ;
+            }
+        }
+        return res ;
+    }
+};