Minimum Lines to Represent a Line Chart

arraymathgeometry

Problem Statement

You are given a 2D integer array stockPrices where stockPrices[i] = [day _i , price _i ] indicates the price of the stock on day day _i is price _i . A line chart is created from the array by plotting the points on an XY plane with the X-axis representing the day and the Y-axis representing the price and connecting adjacent points. One such example is shown below:

Return the minimum number of lines needed to represent the line chart .

Examples

Example 1

Input: stockPrices = [[1,7],[2,6],[3,5],[4,4],[5,4],[6,3],[7,2],[8,1]]
Output: 3
The diagram above represents the input, with the X-axis representing the day and Y-axis representing the price.
The following 3 lines can be drawn to represent the line chart:
- Line 1 (in red) from (1,7) to (4,4) passing through (1,7), (2,6), (3,5), and (4,4).
- Line 2 (in blue) from (4,4) to (5,4).
- Line 3 (in green) from (5,4) to (8,1) passing through (5,4), (6,3), (7,2), and (8,1).
It can be shown that it is not possible to represent the line chart using less than 3 lines.

Example 2

Input: stockPrices = [[3,4],[1,2],[7,8],[2,3]]
Output: 1
As shown in the diagram above, the line chart can be represented with a single line.

Constraints

1 <= stockPrices.length <= 10 ^5

stockPrices[i].length == 2

1 <= day _i , price _i <= 10 ^9

All day _i are distinct .

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicMath