Added some code

leetcode/problems/cpp/number-of-even-and-odd-bits..cpp

@@ -0,0 +1,20 @@
+// by @codeAbinash
+// Time : O(n)
+// Space : O(1)
+
+#include <vector>
+using namespace std;
+
+class Solution {
+ public:
+   vector<int> evenOddBit(int n) {
+      vector<int> ans(2, 0);
+      int i = 0;
+      while (n) {
+         ans[i] += n & 1;
+         n >>= 1;
+         i ^= 1;
+      }
+      return ans;
+   }
+};

leetcode/problems/cpp/sum-of-all-odd-length-subarray.cpp

@@ -0,0 +1,21 @@
+// by @codeAbinash
+// Time : O(n)
+// Space : O(1)
+
+#include "vector"
+using namespace std;
+
+class Solution {
+ public:
+   int sumOddLengthSubarrays(vector<int>& arr) {
+      int n = arr.size();
+      int sum = 0;
+      for (int i = 0; i < n; i++) {
+         int left = i + 1, right = n - i;
+         int left_even = (left + 1) / 2, right_even = (right + 1) / 2;
+         int left_odd = left / 2, right_odd = right / 2;
+         sum += (left_even * right_even + left_odd * right_odd) * arr[i];
+      }
+      return sum;
+   }
+};

leetcode/problems/rs/number-of-even-and-odd-bits.rs

@@ -0,0 +1,17 @@
+// by @codeAbinash
+// Time : O(n)
+// Space : O(1)
+
+impl Solution {
+    pub fn even_odd_bit(n: i32) -> Vec<i32> {
+        let mut ans = vec![0; 2];
+        let mut n = n;
+        let mut i = 0;
+        while n > 0 {
+            ans[i] += n & 1;
+            n >>= 1;
+            i ^= 1;
+        }
+        ans
+    }
+}