You are given a 0-indexed array nums of n integers and an integer target.
You are initially positioned at index 0. In one step, you can jump from index i to any index j such that:
0 <= i < j < n-target <= nums[j] - nums[i] <= targetReturn the maximum number of jumps you can make to reach index n - 1.
If there is no way to reach index n - 1, return -1.
Example 1:
Input: nums = [1,3,6,4,1,2], target = 2 Output: 3 Explanation: To go from index 0 to index n - 1 with the maximum number of jumps, you can perform the following jumping sequence: - Jump from index 0 to index 1. - Jump from index 1 to index 3. - Jump from index 3 to index 5. It can be proven that there is no other jumping sequence that goes from 0 to n - 1 with more than 3 jumps. Hence, the answer is 3.
Example 2:
Input: nums = [1,3,6,4,1,2], target = 3 Output: 5 Explanation: To go from index 0 to index n - 1 with the maximum number of jumps, you can perform the following jumping sequence: - Jump from index 0 to index 1. - Jump from index 1 to index 2. - Jump from index 2 to index 3. - Jump from index 3 to index 4. - Jump from index 4 to index 5. It can be proven that there is no other jumping sequence that goes from 0 to n - 1 with more than 5 jumps. Hence, the answer is 5.
Example 3:
Input: nums = [1,3,6,4,1,2], target = 0 Output: -1 Explanation: It can be proven that there is no jumping sequence that goes from 0 to n - 1. Hence, the answer is -1.
Constraints:
2 <= nums.length == n <= 1000-109 <= nums[i] <= 1090 <= target <= 2 * 109class Solution {
public int maximumJumps(int[] nums, int target) {
int n = nums.length;
int[] memo = new int[n];
Arrays.fill(memo, Integer.MIN_VALUE);
memo[n - 1] = 0;
dfs(nums, target, memo, 0);
return memo[0] > 0 ? memo[0] : -1;
}
private int dfs(int[] nums, int target, int[] memo, int i) {
if (memo[i] > Integer.MIN_VALUE)
return memo[i];
int maxJumps = Integer.MIN_VALUE;
for (int j = i + 1; j < nums.length; j++) {
if (Math.abs(nums[j] - nums[i]) <= target)
maxJumps = Math.max(maxJumps, dfs(nums, target, memo, j) + 1);
}
// System.out.println(Arrays.toString(memo));
return memo[i] = maxJumps;
}
}