Create 3458.Select-K-Disjoint-Special-Substrings.cpp

Author: wisdompeak

Greedy/3458.Select-K-Disjoint-Special-Substrings/3458.Select-K-Disjoint-Special-Substrings.cpp

@@ -0,0 +1,55 @@
+class Solution {
+public:
+    bool maxSubstringLength(string s, int k) 
+    {
+        int n = s.size();        
+        vector<vector<int>>pos(26);
+        for (int i=0; i<n; i++)
+            pos[s[i]-'a'].push_back(i);
+        
+        vector<pair<int, int>>intervals;
+        for (int letter=0; letter<26; letter++)
+        {
+            if (pos[letter].empty()) continue;
+            int start = pos[letter][0];
+            int i = start;
+            int far = pos[letter].back();
+            
+            bool flag = true;
+            while (i<=far)
+            {
+                far = max(far, pos[s[i]-'a'].back());
+                if (pos[s[i]-'a'][0]<start)
+                {
+                    flag = false;
+                    break;
+                }
+                i++;
+            }
+            if (far-start+1==n) continue;
+            if (flag==false) continue;
+            intervals.push_back({start, far});            
+        }
+        
+        return helper(intervals)>=k;
+    }
+    
+    
+    int helper(vector<pair<int, int>> &intervals) {        
+        sort(intervals.begin(), intervals.end(), [](pair<int, int> a, pair<int, int> b) {
+            return a.second < b.second;
+        });
+
+        int count = 0;
+        int far = INT_MIN;
+        
+        for (auto &interval : intervals) 
+        {
+            if (interval.first > far) { 
+                count++;
+                far = interval.second;  
+            }
+        }
+        return count;
+    }
+};