# 149. Max Points on a Line

### Description

 Given *n* points on a 2D plane, find the maximum number of points that lie on the same straight line.

### Constraints

### Approach

### Links

* GeeksforGeeks
* [Leetcode](https://leetcode.com/problems/max-points-on-a-line/)
* ProgramCreek
* YouTube

### **Examples**

{% tabs %}
{% tab title="Example 1" %}
**Input:** \[\[1, 1], \[2, 2], \[3, 3]]

**Output:** 3

**Explanation:**

<div align="left"><img src="/files/-MHbNC4bGAio8D6Qw_1Q" alt=""></div>
{% endtab %}

{% tab title="Example 2" %}
**Input:** \[\[1, 1], \[3, 2], \[5, 3], \[4, 1], \[2, 3], \[1, 4]]

**Output:** 4

**Explanation:**

<div align="left"><img src="/files/-MHbNZaSNcWqpRTrYzPr" alt=""></div>
{% endtab %}
{% endtabs %}

### **Solutions**

{% tabs %}
{% tab title="Solution 1" %}

```java
/**
 * Time complexity : 
 * Space complexity : 
 */

class Solution {
    public int maxPoints(int[][] points) {
        int n = points.length;
        if(n <= 1) return n;
        
        Map<String, Integer> slopeMap = new HashMap();
        int max = 0;
        
        for(int i = 0; i < n; i++) {
            int duplicate = 0;
            int tmpMax = 0;
            
            for(int j = i+1; j < n ; j++) {
                int dx = points[j][0] - points[i][0];
                int dy = points[j][1] - points[i][1];
                if(dx == 0 && dy == 0) {
                    duplicate++;
                } else {
                    String slope = getSlopeKey(dx, dy);
                    slopeMap.put(slope, slopeMap.getOrDefault(slope, 0)+1);
                    tmpMax = Math.max(tmpMax, slopeMap.get(slope));
                }
            }
            max = Math.max(max, tmpMax+duplicate+1);
            slopeMap.clear();
        }
        
        return max;
    }
    
    private String getSlopeKey(int dx, int dy) {
        if(dx == 0) return "0-1";
        if(dy == 0) return "1-0";
        int d = gcd(dx, dy);
        return (dx/d) + "-" + (dy/d);
    }
    
    private int gcd(int a, int b) {
        if(b == 0) return a;
        return gcd(b, a%b);
    }
}
```

{% endtab %}
{% endtabs %}

### **Follow up**

*


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://code-snippets.hbamithkumara.com/leetcode/problems/101-200/max-points-on-a-line.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.