DeleteAndEarn740.kt

package medium

/**
 * 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
 */
fun deleteAndEarn(nums: IntArray): Int {
    var size=0
    val map=HashMap<Int,Int>()
    nums.forEach { num->
        size=Math.max(num,size)
        map[num]=(map[num]?:0)+1
    }
    val dp =IntArray(10001)
    dp[0]=0
    dp[1]=map[1]?:0
    for(i in 2 ..size)
    {
        dp[i]=Math.max(dp[i-1],dp[i-2]+i*(map[i]?:0))
    }
return dp[size]
}