Create 3201. Find the Maximum Length of Valid Subsequence I

3201. Find the Maximum Length of Valid Subsequence I

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+class Solution {
+public:
+    int maximumLength(vector<int>& nums) {
+        int allev = 0, allodd = 0, oddev = 0;
+
+        // Count total even and odd numbers
+        for (int i = 0; i < nums.size(); i++) {
+            if (nums[i] % 2 == 0) {
+                allev++;
+            } else {
+                allodd++;
+            }
+        }
+
+        // Count longest alternating odd-even subsequence
+        bool expectOdd = true;
+        bool expectEven = true;
+        for (int i = 0; i < nums.size(); i++) {
+            if (nums[i] % 2 == 0 && expectEven) {
+                oddev++;
+                expectEven = false;
+                expectOdd = true;
+            } else if (nums[i] % 2 != 0 && expectOdd) {
+                oddev++;
+                expectOdd = false;
+                expectEven = true;
+            }
+        }
+
+        return max({allev, allodd, oddev});
+    }
+};