leetcode 581. Shortest Unsorted Continuous Subarray
作者:互联网
This problem has very detailed solution. So just check out the solution page.
Method 1:
Use monotone stack to record the leftmost and rightmost index.
class Solution {
public int findUnsortedSubarray(int[] nums) {
int N = nums.length;
Stack<Integer> s = new Stack<Integer>();
int l = N, r = 0;
s.add(0);
for (int i = 1; i < N; ++i) {
while (!s.isEmpty() && nums[s.peek()] > nums[i]) {
l = Math.min(l, s.pop());
}
s.push(i);
}
s.clear();
s.add(N - 1);
for (int i = N - 1; i >= 0; --i) {
while (!s.isEmpty() && nums[s.peek()] < nums[i]) {
r = Math.max(r, s.pop());
}
s.push(i);
}
return r >= l ? r - l + 1: 0;
}
}
Method 2:
Sort A and compare with original array
class Solution {
public int findUnsortedSubarray(int[] nums) {
int N = nums.length;
int[] n = Arrays.copyOf(nums, N);
Arrays.sort(n);
int l = 0, r = N - 1;
for (;l < N && n[l] == nums[l]; ++l);
if (l == N) return 0;
for (;r >= 0 && n[r] == nums[r]; --r);
return r - l + 1;
}
}
标签:return,Unsorted,nums,int,Continuous,581,while,pop,&& 来源: https://www.cnblogs.com/exhausttolive/p/10624020.html