题目:
题解:
java
class Solution {
Random random = new Random();
public void wiggleSort(int[] nums) {
int n = nums.length;
int x = (n + 1) / 2;
int mid = x - 1;
int target = findKthLargest(nums, n - mid);
for (int k = 0, i = 0, j = n - 1; k <= j; k++) {
if (nums[transAddress(k, n)] > target) {
while (j > k && nums[transAddress(j, n)] > target) {
j--;
}
swap(nums, transAddress(k, n), transAddress(j--, n));
}
if (nums[transAddress(k, n)] < target) {
swap(nums, transAddress(k, n), transAddress(i++, n));
}
}
}
public int findKthLargest(int[] nums, int k) {
int left = 0, right = nums.length - 1;
while (left <= right) {
int pivot = random.nextInt(right - left + 1) + left;
int newPivot = partitionAroundPivot(left, right, pivot, nums);
if (newPivot == k - 1) {
return nums[newPivot];
} else if (newPivot > k - 1) {
right = newPivot - 1;
} else {
left = newPivot + 1;
}
}
return nums[k - 1];
}
public int transAddress(int i, int n) {
return (2 * n - 2 * i - 1) % (n | 1);
}
public int partitionAroundPivot(int left, int right, int pivot, int[] nums) {
int pivotValue = nums[pivot];
int newPivot = left;
swap(nums, pivot, right);
for (int i = left; i < right; ++i) {
if (nums[i] > pivotValue) {
swap(nums, i, newPivot++);
}
}
swap(nums, right, newPivot);
return newPivot;
}
public void swap(int[] a, int i, int j) {
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}