Day 8 Leet code series, today we will be picking the problem Jump game (https://leetcode.com/problems/jump-game/).

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.

class Solution {
public:
    bool canJump(vector<int>& nums) {
        int maxReachable = 0;
        for(int i = 0; i<nums.size(); i++){
           int val = i + nums[i];
            if(i>maxReachable){
                return false;
            }
            if(val > maxReachable){
                maxReachable = val;
            }
            
        }
        return true;
    }
};

Explaination:

1. We will maintain a maxReachable as a global.
2. Then we will check at every index if index+array[val] is greater than maxReachable then maxReachable is the index+array[val].
3. Also if i > maxReachable i.e. when we can not reach beyond that, then we will return false.