55. Jump Game (Medium)

Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine if you are able to reach the last index.

1. Example 1:

   	  
   	Input: nums = [2,3,1,1,4]
   	Output: true
   	Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.
   	  
   	  

2. Example 2:

   	  
   	Input: nums = [3,2,1,0,4]
   	Output: false
   	Explanation: You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.
   	  
   	  

OCaml Solution

 

let canJump lst =
  let (last_good, last_index) =
    List.fold_left (
       fun (last_good_index, index) x ->
          if (x - (index - last_good_index) >=0) then
            (index, index+1)
	  else
             (last_good_index, index+1)
       ) (0,0) (List.rev lst)
 in
 last_good = last_index - 1
;;


let t1 = canJump [2;3;1;1;4];;
let t2 = canJump [3;2;1;0;4];;
let t3 = canJump [3;0;8;2;0;0;1];;
let t4 =canJump [1;1;2;2;0;1;1];;
let t4 = canJump [2;3;0;1;4];;
let t5 = canJump [4;3;2;1;0];;
let t6 = canJump [1;1;1;1;1];;
let t7 = canJump [2;0;2;0;1];;
let t8 =canJump [2;1;2;2;1;2;2;2];;