3350. Adjacent Increasing Subarrays Detection II.cpp

3350. Adjacent Increasing Subarrays Detection II.cpp

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+#include <iostream>
+using namespace std;
+/*
+APPROACH:
+Use an array to track lengths of increasing streaks, then apply binary search
+to find the largest k for which two adjacent increasing subarrays exist.
+*/
+bool check(int *inc, int n, int k)
+{
+    for (int end1 = k - 1; end1 + k < n; end1++)
+    {
+        if (inc[end1] >= k && inc[end1 + k] >= k)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+int maxIncreasingSubarrays(int *nums, int numsSize)
+{
+    int n = numsSize;
+    int inc[n];
+    for (int i = 0; i < n; i++)
+        inc[i] = 1;
+
+    // Build the increasing streak lengths
+    for (int i = 1; i < n; i++)
+    {
+        if (nums[i] > nums[i - 1])
+        {
+            inc[i] = inc[i - 1] + 1;
+        }
+    }
+
+    int L = 1, R = n / 2;
+    int ans = 0;
+
+    // Binary search for max k
+    while (L <= R)
+    {
+        int mid = L + (R - L) / 2;
+        if (check(inc, n, mid))
+        {
+            ans = mid; // mid works, try bigger k
+            L = mid + 1;
+        }
+        else
+        {
+            R = mid - 1; // mid too big, try smaller k
+        }
+    }
+
+    return ans;
+}