Description (leetcode)

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

submission

impl Solution {
    pub fn can_jump(nums: Vec<i32>) -> bool {
        // the farthest we can reach in each step
        let mut reach = 0;
        for (idx, &step) in nums.iter().enumerate() {
            // this means we can't reach position idx
            // we can't go further, so false
            if reach < idx {
                return false;
            }
            // update reach
            reach = reach.max(idx + step as usize);
        }
        // we reached the end
        true
    }
}