Hoppable - Amazon Top Interview Questions


Problem Statement :


Given an integer list nums where each number represents the maximum number of hops you can make, determine whether you can reach to the last index starting at index 0.

Constraints

n ≤ 100,000 where n is the length of nums.


Example 1

Input
nums = [1, 0, 0, 0]


Output
False



Example 2


Input
nums = [2, 4, 0, 1, 0]


Output
True
Explanation
We can jump from index 0 to 1, and then jump to the end.

Example 3
Input
nums = [1, 1, 0, 1]
Output
False
Explanation
We can't go past index 2 of the array.


Solution :



title-img



                        Solution in C++ :

bool solve(vector<int>& nums) {
    int last = nums.size() - 1;
    for (int i = nums.size() - 1; i >= 0; --i) {
        if (i + nums[i] >= last) last = i;
    }
    return last == 0;
}
                    

                        Solution in Java :

import java.util.*;

class Solution {
    public boolean solve(int[] nums) {
        int reach = 0;
        for (int i = 0; i < nums.length; i++) {
            if (i > reach) {
                return false;
            }
            reach = Math.max(reach, i + nums[i]);
        }
        return true;
    }
}
                    

                        Solution in Python : 
                            
class Solution:
    def solve(self, nums):

        n = len(nums)

        reach = 0
        for i, num in enumerate(nums):
            if i > reach:
                return False

            reach = max(reach, i + nums[i])
            if reach >= n - 1:
                return True
                    

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