Question

740. Delete and Earn

中文文档

Description

You are given an integer array nums. You want to maximize the number of points you get by performing the following operation any number of times:

• Pick any nums[i] and delete it to earn nums[i] points. Afterwards, you must delete every element equal to nums[i] - 1 and every element equal to nums[i] + 1.

Return _the maximum number of points you can earn by applying the above operation some number of times_.

 

Example 1:

Input: nums = [3,4,2]
Output: 6
Explanation: You can perform the following operations:
- Delete 4 to earn 4 points. Consequently, 3 is also deleted. nums = [2].
- Delete 2 to earn 2 points. nums = [].
You earn a total of 6 points.

Example 2:

Input: nums = [2,2,3,3,3,4]
Output: 9
Explanation: You can perform the following operations:
- Delete a 3 to earn 3 points. All 2's and 4's are also deleted. nums = [3,3].
- Delete a 3 again to earn 3 points. nums = [3].
- Delete a 3 once more to earn 3 points. nums = [].
You earn a total of 9 points.

 

Constraints:

• 1 <= nums.length <= 2 * 104
• 1 <= nums[i] <= 104

Solutions

Solution 1

class Solution:
  def deleteAndEarn(self, nums: List[int]) -> int:
    mx = -inf
    for num in nums:
      mx = max(mx, num)
    total = [0] * (mx + 1)
    for num in nums:
      total[num] += num
    first = total[0]
    second = max(total[0], total[1])
    for i in range(2, mx + 1):
      cur = max(first + total[i], second)
      first = second
      second = cur
    return second

class Solution {
  public int deleteAndEarn(int[] nums) {
    if (nums.length == 0) {
      return 0;
    }

    int[] sums = new int[10010];
    int[] select = new int[10010];
    int[] nonSelect = new int[10010];

    int maxV = 0;
    for (int x : nums) {
      sums[x] += x;
      maxV = Math.max(maxV, x);
    }

    for (int i = 1; i <= maxV; i++) {
      select[i] = nonSelect[i - 1] + sums[i];
      nonSelect[i] = Math.max(select[i - 1], nonSelect[i - 1]);
    }
    return Math.max(select[maxV], nonSelect[maxV]);
  }
}

class Solution {
public:
  int deleteAndEarn(vector<int>& nums) {
    vector<int> vals(10010);
    for (int& num : nums) {
      vals[num] += num;
    }
    return rob(vals);
  }

  int rob(vector<int>& nums) {
    int a = 0, b = nums[0];
    for (int i = 1; i < nums.size(); ++i) {
      int c = max(nums[i] + a, b);
      a = b;
      b = c;
    }
    return b;
  }
};

func deleteAndEarn(nums []int) int {

  max := func(x, y int) int {
    if x > y {
      return x
    }
    return y
  }

  mx := math.MinInt32
  for _, num := range nums {
    mx = max(mx, num)
  }
  total := make([]int, mx+1)
  for _, num := range nums {
    total[num] += num
  }
  first := total[0]
  second := max(total[0], total[1])
  for i := 2; i <= mx; i++ {
    cur := max(first+total[i], second)
    first = second
    second = cur
  }
  return second
}