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Author: MishkatIT

1766-minimum-number-of-removals-to-make-mountain-array/1766-minimum-number-of-removals-to-make-mountain-array.cpp

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+class Solution {
+public:
+    int minimumMountainRemovals(vector<int>& v) {
+        int n = v.size();
+        vector<int> lis(n, 1), lds(n, 1);
+        for (int i = 0; i < n; i++) {
+            int mx = 0;
+            for (int j = i - 1; j >= 0; j--) {
+                if (v[j] < v[i]) {
+                    mx = max(mx, lis[j]);
+                }
+            }
+            lis[i] += mx;
+        }
+        for (int i = n - 1; i >= 0; i--) {
+            int mx = 0;
+            for (int j = i + 1; j < n; j++) {
+                if (v[i] > v[j]) {
+                    mx = max(mx, lds[j]);
+                }
+            }
+            lds[i] += mx;
+        }
+        int ans = n;
+        for (int i = 0; i < n; i++) {
+            if (lis[i] == 1 || lds[i] == 1) continue;
+            ans = min(ans, n - lis[i] - lds[i] + 1);
+        }
+        return ans;
+    }
+};