1642 - Furthest Building You Can Reach\.

Medium

You are given an integer array heights representing the heights of buildings, some bricks, and some ladders.

You start your journey from building 0 and move to the next building by possibly using bricks or ladders.

While moving from building i to building i+1 ( 0-indexed ),

• If the current building's height is greater than or equal to the next building's height, you do not need a ladder or bricks.

• If the current building's height is less than the next building's height, you can either use one ladder or (h[i+1] - h[i]) bricks.

Return the furthest building index (0-indexed) you can reach if you use the given ladders and bricks optimally.

Example 1:

Input: heights = 4,2,7,6,9,14,12, bricks = 5, ladders = 1

Output: 4

Explanation: Starting at building 0, you can follow these steps:

• Go to building 1 without using ladders nor bricks since 4 >= 2.

• Go to building 2 using 5 bricks. You must use either bricks or ladders because 2 < 7.

• Go to building 3 without using ladders nor bricks since 7 >= 6.

• Go to building 4 using your only ladder. You must use either bricks or ladders because 6 < 9.

It is impossible to go beyond building 4 because you do not have any more bricks or ladders.

Example 2:

Input: heights = 4,12,2,7,3,18,20,3,19, bricks = 10, ladders = 2

Output: 7

Example 3:

Input: heights = 14,3,19,3, bricks = 17, ladders = 0

Output: 3

Constraints:

• <code>1 <= heights.length <= 10⁵</code>

• <code>1 <= heightsi<= 10⁶</code>

• <code>0 <= bricks <= 10⁹</code>

• 0 <= ladders <= heights.length