Merge pull request #86 from SenthilkumarKailash/feature/3516-Find-Closest-Person

Solution #3516 - Kailash Senthilkumar - 09/08/2025

Author: JRS296

Math/#3516-Find-Closest-Person-Easy/Explanation.md

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+# Find Closest Person
+
+**Difficulty:** Easy  
+**Category:** Math, Simulation  
+**Leetcode Link:** [Problem Link](https://leetcode.com/problems/find-closest-person/)  
+
+---
+
+## 📝 Introduction
+
+We are given three integers `x`, `y`, and `z` representing positions of three people on a number line:
+- Person 1 is at position `x`.
+- Person 2 is at position `y`.
+- Person 3 is at position `z` (stationary).
+
+Both Person 1 and Person 2 move toward Person 3 at the same speed.  
+We must determine which person reaches Person 3 first:
+- Return `1` if Person 1 arrives first.
+- Return `2` if Person 2 arrives first.
+- Return `0` if both arrive at the same time.
+
+---
+
+## 💡 Approach & Key Insights
+
+The problem reduces to comparing **absolute distances** from each person to Person 3:
+- `dist1 = abs(x - z)`
+- `dist2 = abs(y - z)`
+
+The smaller distance determines who reaches first. If both distances are equal, both reach at the same time.
+
+---
+
+## 🛠️ Breakdown of Approaches
+
+### 1️⃣ Direct Distance Comparison
+
+- **Explanation:**  
+  Compute the absolute difference in positions between each moving person and Person 3. Compare distances to decide the result.
+- **Time Complexity:** O(1) — Only two distance calculations and a comparison.
+- **Space Complexity:** O(1) — Only a few variables are used.
+
+Example:  
+```
+x = 2, y = 7, z = 4
+dist1 = |2 - 4| = 2
+dist2 = |7 - 4| = 3
+Output: 1 (Person 1 arrives first)
+```
+
+---
+
+## 📊 Complexity Analysis
+
+| Approach        | Time Complexity | Space Complexity |
+| --------------- | --------------- | ---------------- |
+| Distance Compare| O(1)            | O(1)             |
+
+---
+
+## 📌 Example Walkthroughs & Dry Runs
+
+Example 1:  
+```
+Input: x = 2, y = 7, z = 4
+dist1 = 2, dist2 = 3
+Result: 1
+```
+
+Example 2:  
+```
+Input: x = 2, y = 5, z = 6
+dist1 = 4, dist2 = 1
+Result: 2
+```
+
+Example 3:  
+```
+Input: x = 1, y = 5, z = 3
+dist1 = 2, dist2 = 2
+Result: 0
+```
+
+---
+
+## 🔗 Additional Resources
+
+- [Absolute Value in Programming](https://en.wikipedia.org/wiki/Absolute_value)
+- [LeetCode Simulation Problems](https://leetcode.com/tag/simulation/)
+
+---
+
+Author: Kailash Senthilkumar  
+Date: 09/08/2025  

Math/#3516-Find-Closest-Person-Easy/Solution.cpp

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+class Solution {
+public:
+    int findClosestPerson(int x, int y, int z) {
+        int dist1 = abs(x - z);
+        int dist2 = abs(y - z);
+
+        if (dist1 < dist2) return 1;
+        else if (dist2 < dist1) return 2;
+        else return 0;
+    }
+};

Math/#3516-Find-Closest-Person-Easy/Solution.java

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+class Solution {
+    public int findClosest(int x, int y, int z) {
+        int dist1 = Math.abs(x - z);
+        int dist2 = Math.abs(y - z);
+
+        if (dist1 < dist2) return 1;
+        else if (dist2 < dist1) return 2;
+        else return 0;
+        
+    }
+}

Math/#3516-Find-Closest-Person-Easy/Solution.py

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+class Solution:
+    def findClosestPerson(self, x: int, y: int, z: int) -> int:
+        dist1 = abs(x - z)
+        dist2 = abs(y - z)
+
+        if dist1 < dist2:
+            return 1
+        elif dist2 < dist1:
+            return 2
+        else:
+            return 0