Given a sorted array of integers nums and integer values a, b and c. Apply a function of the form f(x) = ax2 + bx + c to each element x in the array.
The returned array must be in** sorted order**.
Expected time complexity: O(n)
Example:
nums = [-4, -2, 2, 4], a = 1, b = 3, c = 5,
Result: [3, 9, 15, 33]
nums = [-4, -2, 2, 4], a = -1, b = 3, c = 5
Result: [-23, -5, 1, 7]
一刷
题解：
当a大于0时，(f(a)+f(b))/2 > f((a+b)/2)
当a小于0时，(f(a)+f(b))/2 < f((a+b)/2)
example
从数组首位两端开始寻找最值
class Solution {
public int[] sortTransformedArray(int[] nums, int a, int b, int c) {
int n = nums.length;
int[] sorted = new int[n];
int i = 0, j = n-1;
int index = a>=0? n-1:0;
while(i<=j){
if(a>=0){
sorted[index--] = quad(nums[i], a,b,c) >= quad(nums[j], a,b,c)? quad(nums[i++], a, b, c) : quad(nums[j--], a, b, c);
}else{
sorted[index++] = quad(nums[i], a,b,c) >= quad(nums[j], a,b,c)? quad(nums[j--], a, b, c) : quad(nums[i++], a, b, c);
}
}
return sorted;
}
private int quad(int x, int a, int b, int c) {
return a * x * x + b * x + c;
}
}
