Runtime: 3 ms (Top 97.81%) | Memory: 12.70 MB (Top 49.02%)

Author: AnasImloul

scripts/algorithms/M/Max Chunks To Make Sorted II/Max Chunks To Make Sorted II.cpp

@@ -1,48 +1,20 @@
-class BIT {
- public:
-  BIT(int capacity) : nodes(capacity + 1, 0) {}
-  BIT(const vector<int>& nums) : nodes(nums.size() + 1, 0) {
-    for (int i = 0; i < nums.size(); ++i) {
-      update(i + 1, nums[i]);
-    }
-  }
-
-  void update(int idx, int val) {
-    for (int i = idx; i < nodes.size(); i += i & -i) {
-      nodes[i] += val;
-    }
-  }
-
-  int query(int idx) {
-    int ans = 0;
-    for (int i = idx; i > 0; i -= i & -i) {
-      ans += nodes[i];
-    }
-    return ans;
-  }
-
- private:
-  vector<int> nodes;
-};
+// Runtime: 3 ms (Top 97.81%) | Memory: 12.70 MB (Top 49.02%)
 
 class Solution {
- public:
-  int maxChunksToSorted(vector<int>& arr) {
-    int n = arr.size();
-    BIT bit(n);
-    unordered_map<int, int> h;
-    vector<int> sorted = arr;
-    sort(sorted.begin(), sorted.end());
-    for (int i = 0; i < n; ++i) {
-      if (i == 0 || sorted[i - 1] != sorted[i]) h[sorted[i]] = i + 1;
-    }
-
-    int ans = 0;
-    for (int i = 0; i < n; ++i) {
-      bit.update(h[arr[i]], 1);
-      ++h[arr[i]];
-      if (bit.query(i + 1) == i + 1) ans += 1;
+public:
+    int maxChunksToSorted(vector<int>& arr) {
+        vector<int>right(arr.size()+1);
+        right[arr.size()] = INT_MAX;
+        
+        for(int i =arr.size()-1 ; i>= 0; i--){
+           right[i] = min(right[i+1], arr[i]);
+        }
+        int left_max = INT_MIN;
+        int count_chunks =0;
+        for(int i =0; i<arr.size(); i++){
+            left_max = max(left_max, arr[i]);
+            if(left_max <= right[i+1]) count_chunks++;  
+        }
+        return count_chunks;
     }
-    return ans;
-  }
 };