Jump Game

Problem Statement

You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length at that position.

Return true if you can reach the last index, or false otherwise.

LeetCode link

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.

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.

Constraints:

• 1 <= nums.length <= 10^4
• 0 <= nums[i] <= 10^5

Code

Java Code

public boolean canJump(int[] A) {
    if(A.length <= 1)
        return true;

    int max = A[0]; //max stands for the largest index that can be reached.

    for(int i=0; i<A.length; i++){
        //if not enough to go to next
        if(max <= i && A[i] == 0)
            return false;

        //update max
        if(i + A[i] > max){
            max = i + A[i];
        }

        //max is enough to reach the end
        if(max >= A.length-1)
            return true;
    }

    return false;
}