Description

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.

给定一个非负整型数组，每个数字表示可以从该位置向后跳跃的最大步数。

判断是否能从第一个数字开始跳跃到最后一个数字。

Solution

  • 使用reachable表示当前可跳跃的最远位置；
  • 从第一个位置开始向reachable搜索，并更新reachable；
  • 如果reachable >= len(nums) - 1表示可达最后一个数字。
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func canJump(nums []int) bool {
    target := len(nums) - 1

    if target < 0 {
        return false
    }

    // 可到达的最远距离
    reachable := 0

    // 从 0 到 reachable
    for i := 0; i <= reachable; i++ {
        m := nums[i] + i
        if m > reachable {
            reachable = m
        }

        if reachable >= target {
            return true
        }
    }

    return reachable >= target
}