> For the complete documentation index, see [llms.txt](https://timmybeeflin.gitbook.io/cracking-leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://timmybeeflin.gitbook.io/cracking-leetcode/stack-and-queue/946.-validate-stack-sequences.md).

# 946. Validate Stack Sequences

```
T: O(n)
S: O(n)
```

````java
```java
class Solution {
    public boolean validateStackSequences(int[] pushed, int[] popped) {
        Stack<Integer> stack = new Stack<>();
        int j = 0;

        for (int i = 0; i < pushed.length; i++) {
            stack.push(pushed[i]);
            while (!stack.isEmpty() && stack.peek() == popped[j]) {
                stack.pop();
                j++;
            }
        }
        return stack.isEmpty();
    }
}


/*




T: O(n)
s: O(n)

*/
```
````