LeetCode-in-Java
2640. Find the Score of All Prefixes of an Array
Medium
We define the conversion array conver of an array arr as follows:
conver[i] = arr[i] + max(arr[0..i])wheremax(arr[0..i])is the maximum value ofarr[j]over0 <= j <= i.
We also define the score of an array arr as the sum of the values of the conversion array of arr.
Given a 0-indexed integer array nums of length n, return an array ans of length n where ans[i] is the score of the prefix nums[0..i].
Example 1:
Input: nums = [2,3,7,5,10]
Output: [4,10,24,36,56]
Explanation:
For the prefix [2], the conversion array is [4] hence the score is 4
For the prefix [2, 3], the conversion array is [4, 6] hence the score is 10
For the prefix [2, 3, 7], the conversion array is [4, 6, 14] hence the score is 24
For the prefix [2, 3, 7, 5], the conversion array is [4, 6, 14, 12] hence the score is 36
For the prefix [2, 3, 7, 5, 10], the conversion array is [4, 6, 14, 12, 20] hence the score is 56
Example 2:
Input: nums = [1,1,2,4,8,16]
Output: [2,4,8,16,32,64]
Explanation:
For the prefix [1], the conversion array is [2] hence the score is 2
For the prefix [1, 1], the conversion array is [2, 2] hence the score is 4
For the prefix [1, 1, 2], the conversion array is [2, 2, 4] hence the score is 8
For the prefix [1, 1, 2, 4], the conversion array is [2, 2, 4, 8] hence the score is 16
For the prefix [1, 1, 2, 4, 8], the conversion array is [2, 2, 4, 8, 16] hence the score is 32
For the prefix [1, 1, 2, 4, 8, 16], the conversion array is [2, 2, 4, 8, 16, 32] hence the score is 64
Constraints:
1 <= nums.length <= 1051 <= nums[i] <= 109
Solution
public class Solution {
public long[] findPrefixScore(int[] nums) {
int max = Integer.MIN_VALUE;
long sum = 0L;
long[] res = new long[nums.length];
for (int i = 0; i < nums.length; i++) {
int curr = nums[i];
max = Math.max(max, curr);
sum += max + curr;
res[i] = sum;
}
return res;
}
}