fix(posts): fetch daily from files

public/code/algorithms/leetcode-daily/cfps-twoptr.py

@@ -0,0 +1,16 @@
+def countFairPairs(self, nums, lower, upper):
+    nums.sort()
+    ans = 0
+
+    def pairs_leq(x: int) -> int:
+        pairs = 0
+        l, r = 0, len(nums) - 1
+        while l < r:
+            if nums[l] + nums[r] <= x:
+                pairs += r - l
+                l += 1
+            else:
+                r -= 1
+        return pairs
+
+    return pairs_leq(upper) - pairs_leq(lower - 1)