Jump Game — LeetCode #55

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.

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 <= 104
• 0 <= nums[i] <= 105

Solutions:

Python

class Solution:
    def canJump(self, nums: List[int]) -> bool:
        n = len(nums)
        if n == 0:
            return False
        if n == 1:
            return True
        
        max_reach = 0
        for i in range(n):
            if i > max_reach:
                return False
            max_reach = max(max_reach, i + nums[i])
            if max_reach >= n - 1:
                return True
        
        return False

C#

class Solution {
    public bool CanJump(int[] nums) {
        int n = nums.Length;
        if (n == 0) {
            return false;
        }
        if (n == 1) {
            return true;
        }

        int maxReach = 0;
        for (int i = 0; i < n; i++) {
            if (i > maxReach) {
                return false;
            }
            maxReach = Math.Max(maxReach, i + nums[i]);
            if (maxReach >= n - 1) {
                return true;
            }
        }

        return false;
    }
}

Java

class Solution {
    public boolean canJump(int[] nums) {
        int n = nums.length;
        if (n == 0) {
            return false;
        }
        if (n == 1) {
            return true;
        }

        int maxReach = 0;
        for (int i = 0; i < n; i++) {
            if (i > maxReach) {
                return false;
            }
            maxReach = Math.max(maxReach, i + nums[i]);
            if (maxReach >= n - 1) {
                return true;
            }
        }

        return false;
    }
}

Javascript

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var canJump = function(nums) {
    const n = nums.length;
    if (n === 0) {
        return false;
    }
    if (n === 1) {
        return true;
    }

    let maxReach = 0;
    for (let i = 0; i < n; i++) {
        if (i > maxReach) {
            return false;
        }
        maxReach = Math.max(maxReach, i + nums[i]);
        if (maxReach >= n - 1) {
            return true;
        }
    }

    return false;
};

Typescript

function canJump(nums: number[]): boolean {
    const n = nums.length;
    if (n === 0) {
        return false;
    }
    if (n === 1) {
        return true;
    }

    let maxReach = 0;
    for (let i = 0; i < n; i++) {
        if (i > maxReach) {
            return false;
        }
        maxReach = Math.max(maxReach, i + nums[i]);
        if (maxReach >= n - 1) {
            return true;
        }
    }

    return false;
}

PHP

class Solution {

    /**
     * @param Integer[] $nums
     * @return Boolean
     */
    function canJump($nums) {
        $n = count($nums);
        if ($n == 0) {
            return false;
        }
        if ($n == 1) {
            return true;
        }

        $maxReach = 0;
        for ($i = 0; $i < $n; $i++) {
            if ($i > $maxReach) {
                return false;
            }
            $maxReach = max($maxReach, $i + $nums[$i]);
            if ($maxReach >= $n - 1) {
                return true;
            }
        }

        return false;
    }

}

I hope this helps! Let me know if you have any questions. Don’t forget to FOLLOW and give some CLAPS to support my content