55_jump_game.cpp

/*
LeetCode 55 - Jump Game
Difficulty: Medium

Problem:
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 <= 10^4
    0 <= nums[i] <= 10^5

Time Complexity: O(n)
Space Complexity: O(1)
*/

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

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

int main() {
    Solution solution;

    vector<int> nums1 = {2, 3, 1, 1, 4};
    cout << (solution.canJump(nums1) ? "true" : "false") << endl;  // true

    vector<int> nums2 = {3, 2, 1, 0, 4};
    cout << (solution.canJump(nums2) ? "true" : "false") << endl;  // false

    return 0;
}