jump-game.js

/**
 * Jump Game
 *
 * Given an array of non-negative integers, you are initially positioned at the first index of the array.
 *
 * Each element in the array represents your maximum jump length at that position.
 *
 * Determine if you are able to reach the last index.
 *
 * Example 1:
 *
 * Input: [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: [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.
 */

/**
 * @param {number[]} nums
 * @return {boolean}
 */
const canJump = nums => {
  let reach = 0;

  for (let i = 0; i < nums.length && i <= reach; i++) {
    if (i + nums[i] > reach) {
      reach = i + nums[i];
    }
  }

  return reach >= nums.length - 1;
};

export { canJump };