# 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 :

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

## Square-Ten Tree

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## Balanced Forest

Greg has a tree of nodes containing integer data. He wants to insert a node with some non-zero integer value somewhere into the tree. His goal is to be able to cut two edges and have the values of each of the three new trees sum to the same amount. This is called a balanced forest. Being frugal, the data value he inserts should be minimal. Determine the minimal amount that a new node can have to a

## Jenny's Subtrees

Jenny loves experimenting with trees. Her favorite tree has n nodes connected by n - 1 edges, and each edge is ` unit in length. She wants to cut a subtree (i.e., a connected part of the original tree) of radius r from this tree by performing the following two steps: 1. Choose a node, x , from the tree. 2. Cut a subtree consisting of all nodes which are not further than r units from node x .

## Tree Coordinates

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## Array Pairs

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## Self Balancing Tree

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