0946. Validate Stack Sequences

# 946. Validate Stack Sequences#

## 题目 #

Given two sequences pushed and popped with distinct values, return true if and only if this could have been the result of a sequence of push and pop operations on an initially empty stack.

Example 1:

``````
Input: pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
Output: true
Explanation: We might do the following sequence:
push(1), push(2), push(3), push(4), pop() -> 4,
push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1

``````

Example 2:

``````
Input: pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
Output: false
Explanation: 1 cannot be popped before 2.

``````

Note:

1. 0 <= pushed.length == popped.length <= 1000
2. 0 <= pushed[i], popped[i] < 1000
3. pushed is a permutation of popped.
4. pushed and popped have distinct values.

## 代码 #

``````
package leetcode

func validateStackSequences(pushed []int, popped []int) bool {
stack, j, N := []int{}, 0, len(pushed)
for _, x := range pushed {
stack = append(stack, x)
for len(stack) != 0 && j < N && stack[len(stack)-1] == popped[j] {
stack = stack[0 : len(stack)-1]
j++
}
}
return j == N
}

``````

Apr 8, 2023