From 7384a33f3ac1200686d50e8720fc6675edc83a24 Mon Sep 17 00:00:00 2001
From: Prad Nukala <prad@sonr.io>
Date: Fri, 28 Aug 2026 15:52:39 -0400
Subject: [PATCH] feat: Add car fleet

---
 apps/docs/content/(array)/853-car-fleet.mdx | 47 ++++++++++
 work/Medium/Array/853.car-fleet.py          | 98 +++++++++++++++++++++
 2 files changed, 145 insertions(+)
 create mode 100644 apps/docs/content/(array)/853-car-fleet.mdx
 create mode 100644 work/Medium/Array/853.car-fleet.py

diff --git a/apps/docs/content/(array)/853-car-fleet.mdx b/apps/docs/content/(array)/853-car-fleet.mdx
new file mode 100644
index 0000000..f05f906
--- /dev/null
+++ b/apps/docs/content/(array)/853-car-fleet.mdx
@@ -0,0 +1,47 @@
+---
+title: '853. Car Fleet'
+description: There are n cars at given miles away from the starting mile 0, traveling to reach the mile target
+sidebar:
+  label: 'Car Fleet'
+  badge: 'Medium'
+---
+
+<Badge variant="accent">Monotonic Stack</Badge>
+
+### Example 1:
+- Input: `target = 12, position = [10,8,0,5,3], speed = [2,4,1,1,3]`
+- Output: `3`
+- Explanation: • The cars starting at `10 (speed 2`) and `8 (speed 4`) become a fleet, meeting each other at `12`. The fleet forms at `target`. • The car starting at `0 (speed 1`) does not catch up to any other car, so it is a fleet by itself. • The cars starting at `5 (speed 1`) and `3 (speed 3`) become a fleet, meeting each other at `6`. The fleet moves at `speed 1` until it reaches `target`.
+
+### Example 2:
+- Input: `target = 10, position = [3], speed = [3]`
+- Output: `1`
+- Explanation: There is only one car, hence there is only one fleet.
+
+### Example 3:
+- Input: `target = 100, position = [0,2,4], speed = [4,2,1]`
+- Output: `1`
+- Explanation: • The cars starting at `0 (speed 4`) and `2 (speed 2`) become a fleet, meeting each other at `4`. The car starting at `4 (speed 1`) travels to `5`. • Then, the fleet at `4 (speed 2`) and the car at `position 5 (speed 1`) become one fleet, meeting each other at `6`. The fleet moves at `speed 1` until it reaches `target`.
+
+### Constraints:
+
+- `n == position.length == speed.length`
+- `1 <= n <= 10^5`
+- `0 < target <= 10^6`
+- `0 <= position[i] < target`
+- All the values of `position` are unique.
+- `0 < speed[i] <= 10^6`
+
+## Solution
+
+```py
+class Solution:
+    def carFleet(self, target: int, position: List[int], speed: List[int]) -> int:
+        stack = []
+        for pos, spd in sorted(zip(position, speed), reverse=True):
+            time = (target - pos) / spd
+            if not stack or time > stack[-1]:
+                stack.append(time)
+
+        return len(stack)
+```
diff --git a/work/Medium/Array/853.car-fleet.py b/work/Medium/Array/853.car-fleet.py
new file mode 100644
index 0000000..9613f7c
--- /dev/null
+++ b/work/Medium/Array/853.car-fleet.py
@@ -0,0 +1,98 @@
+"""
+853. Car Fleet
+Difficulty: Medium
+https://leetcode.com/problems/car-fleet/
+
+──────────────────────────────────────────────────
+
+There are n cars at given miles away from the starting mile 0,
+traveling to reach the mile target.
+
+You are given two integer arrays position and speed, both of length
+n, where position[i] is the starting mile of the i^th car and speed[i]
+is the speed of the i^th car in miles per hour.
+
+A car cannot pass another car, but it can catch up and then travel
+next to it at the speed of the slower car.
+
+A car fleet is a single car or a group of cars driving next to each
+other. The speed of the car fleet is the minimum speed of any car in
+the fleet.
+
+If a car catches up to a car fleet at the mile target, it will still
+be considered as part of the car fleet.
+
+Return the number of car fleets that will arrive at the destination.
+
+
+
+Example 1:
+
+Input: target = 12, position = [10,8,0,5,3], speed = [2,4,1,1,3]
+
+Output: 3
+
+Explanation:
+
+• The cars starting at 10 (speed 2) and 8 (speed 4) become a fleet,
+meeting each other at 12. The fleet forms at target.
+
+• The car starting at 0 (speed 1) does not catch up to any other
+car, so it is a fleet by itself.
+
+• The cars starting at 5 (speed 1) and 3 (speed 3) become a fleet,
+meeting each other at 6. The fleet moves at speed 1 until it reaches
+target.
+
+Example 2:
+
+Input: target = 10, position = [3], speed = [3]
+
+Output: 1
+
+Explanation:
+
+There is only one car, hence there is only one fleet.
+
+Example 3:
+
+Input: target = 100, position = [0,2,4], speed = [4,2,1]
+
+Output: 1
+
+Explanation:
+
+• The cars starting at 0 (speed 4) and 2 (speed 2) become a fleet,
+meeting each other at 4. The car starting at 4 (speed 1) travels to 5.
+
+• Then, the fleet at 4 (speed 2) and the car at position 5 (speed 1)
+become one fleet, meeting each other at 6. The fleet moves at speed 1
+until it reaches target.
+
+
+
+Constraints:
+
+        • n == position.length == speed.length
+
+        • 1 <= n <= 10^5
+
+        • 0 < target <= 10^6
+
+        • 0 <= position[i] < target
+
+        • All the values of position are unique.
+
+        • 0 < speed[i] <= 10^6
+"""
+
+
+class Solution:
+    def carFleet(self, target: int, position: List[int], speed: List[int]) -> int:
+        stack = []
+        for pos, spd in sorted(zip(position, speed), reverse=True):
+            time = (target - pos) / spd
+            if not stack or time > stack[-1]:
+                stack.append(time)
+
+        return len(stack)