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Jul 20, 2024
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feat: add solutions to lc problem: No.0946 #3294

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108 changes: 54 additions & 54 deletions solution/0900-0999/0946.Validate Stack Sequences/README.md
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -60,11 +60,9 @@ push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1

### 方法一：栈模拟

遍历 `pushed` 序列，将每个数 `v` 依次压入栈中，压入后检查这个数是不是 `popped` 序列中下一个要弹出的值，如果是就循环把栈顶元素弹出。
我们遍历 $\textit{pushed}$ 数组，对于当前遍历到的元素 $x$，我们将其压入栈 $\textit{stk}$ 中，然后判断栈顶元素是否和 $\textit{popped}$ 数组中下一个要弹出的元素相等，如果相等，我们就将栈顶元素弹出并将 $\textit{popped}$ 数组中下一个要弹出的元素的索引 $i$ 加一。最后，如果要弹出的元素都能按照 $\textit{popped}$ 数组的顺序弹出，返回 $\textit{true}$，否则返回 $\textit{false}$。

遍历结束，如果 `popped` 序列已经到末尾，说明是一个合法的序列，否则不是。

时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 是 `pushed` 序列的长度。
时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 为 $\textit{pushed}$ 数组的长度。

<!-- tabs:start -->

Expand All @@ -73,13 +71,14 @@ push(5), pop() -&gt; 5, pop() -&gt; 3, pop() -&gt; 2, pop() -&gt; 1
```python
class Solution:
def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
j, stk = 0, []
for v in pushed:
stk.append(v)
while stk and stk[-1] == popped[j]:
stk = []
i = 0
for x in pushed:
stk.append(x)
while stk and stk[-1] == popped[i]:
stk.pop()
j += 1
return j == len(pushed)
i += 1
return i == len(popped)
```

#### Java
Expand All @@ -88,15 +87,15 @@ class Solution:
class Solution {
public boolean validateStackSequences(int[] pushed, int[] popped) {
Deque<Integer> stk = new ArrayDeque<>();
int j = 0;
for (int v : pushed) {
stk.push(v);
while (!stk.isEmpty() && stk.peek() == popped[j]) {
int i = 0;
for (int x : pushed) {
stk.push(x);
while (!stk.isEmpty() && stk.peek() == popped[i]) {
stk.pop();
++j;
++i;
}
}
return j == pushed.length;
return i == popped.length;
}
}
```
Expand All @@ -108,15 +107,15 @@ class Solution {
public:
bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
stack<int> stk;
int j = 0;
for (int v : pushed) {
stk.push(v);
while (!stk.empty() && stk.top() == popped[j]) {
int i = 0;
for (int x : pushed) {
stk.push(x);
while (stk.size() && stk.top() == popped[i]) {
stk.pop();
++j;
++i;
}
}
return j == pushed.size();
return i == popped.size();
}
};
```
Expand All @@ -126,32 +125,32 @@ public:
```go
func validateStackSequences(pushed []int, popped []int) bool {
stk := []int{}
j := 0
for _, v := range pushed {
stk = append(stk, v)
for len(stk) > 0 && stk[len(stk)-1] == popped[j] {
i := 0
for _, x := range pushed {
stk = append(stk, x)
for len(stk) > 0 && stk[len(stk)-1] == popped[i] {
stk = stk[:len(stk)-1]
j++
i++
}
}
return j == len(pushed)
return i == len(popped)
}
```

#### TypeScript

```ts
function validateStackSequences(pushed: number[], popped: number[]): boolean {
const stk = [];
let j = 0;
for (const v of pushed) {
stk.push(v);
while (stk.length && stk[stk.length - 1] == popped[j]) {
const stk: number[] = [];
let i = 0;
for (const x of pushed) {
stk.push(x);
while (stk.length && stk.at(-1)! === popped[i]) {
stk.pop();
++j;
i++;
}
}
return j == pushed.length;
return i === popped.length;
}
```

Expand All @@ -160,16 +159,16 @@ function validateStackSequences(pushed: number[], popped: number[]): boolean {
```rust
impl Solution {
pub fn validate_stack_sequences(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
let mut stack = Vec::new();
let mut stk: Vec<i32> = Vec::new();
let mut i = 0;
for &num in pushed.iter() {
stack.push(num);
while !stack.is_empty() && *stack.last().unwrap() == popped[i] {
stack.pop();
for &x in &pushed {
stk.push(x);
while !stk.is_empty() && *stk.last().unwrap() == popped[i] {
stk.pop();
i += 1;
}
}
stack.len() == 0
i == popped.len()
}
}
```
Expand All @@ -183,16 +182,16 @@ impl Solution {
* @return {boolean}
*/
var validateStackSequences = function (pushed, popped) {
let stk = [];
let j = 0;
for (const v of pushed) {
stk.push(v);
while (stk.length && stk[stk.length - 1] == popped[j]) {
const stk = [];
let i = 0;
for (const x of pushed) {
stk.push(x);
while (stk.length && stk.at(-1) === popped[i]) {
stk.pop();
++j;
i++;
}
}
return j == pushed.length;
return i === popped.length;
};
```

Expand All @@ -202,16 +201,17 @@ var validateStackSequences = function (pushed, popped) {
public class Solution {
public bool ValidateStackSequences(int[] pushed, int[] popped) {
Stack<int> stk = new Stack<int>();
int j = 0;
foreach (int x in pushed)
{
int i = 0;

foreach (int x in pushed) {
stk.Push(x);
while (stk.Count != 0 && stk.Peek() == popped[j]) {
while (stk.Count > 0 && stk.Peek() == popped[i]) {
stk.Pop();
++j;
i++;
}
}
return stk.Count == 0;

return i == popped.Length;
}
}
```
Expand Down
108 changes: 57 additions & 51 deletions solution/0900-0999/0946.Validate Stack Sequences/README_EN.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,11 @@ pop() -&gt; 5, pop() -&gt; 3, pop() -&gt; 2, pop() -&gt; 1

<!-- solution:start -->

### Solution 1
### Solution 1: Stack Simulation

We iterate through the $\textit{pushed}$ array. For the current element $x$ being iterated, we push it into the stack $\textit{stk}$. Then, we check if the top element of the stack is equal to the next element to be popped in the $\textit{popped}$ array. If they are equal, we pop the top element from the stack and increment the index $i$ of the next element to be popped in the $\textit{popped}$ array. Finally, if all elements can be popped in the order specified by the $\textit{popped}$ array, return $\textit{true}$; otherwise, return $\textit{false}$.

The time complexity is $O(n)$, and the space complexity is $O(n)$. Here, $n$ is the length of the $\textit{pushed}$ array.

<!-- tabs:start -->

Expand All @@ -67,13 +71,14 @@ pop() -&gt; 5, pop() -&gt; 3, pop() -&gt; 2, pop() -&gt; 1
```python
class Solution:
def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
j, stk = 0, []
for v in pushed:
stk.append(v)
while stk and stk[-1] == popped[j]:
stk = []
i = 0
for x in pushed:
stk.append(x)
while stk and stk[-1] == popped[i]:
stk.pop()
j += 1
return j == len(pushed)
i += 1
return i == len(popped)
```

#### Java
Expand All @@ -82,15 +87,15 @@ class Solution:
class Solution {
public boolean validateStackSequences(int[] pushed, int[] popped) {
Deque<Integer> stk = new ArrayDeque<>();
int j = 0;
for (int v : pushed) {
stk.push(v);
while (!stk.isEmpty() && stk.peek() == popped[j]) {
int i = 0;
for (int x : pushed) {
stk.push(x);
while (!stk.isEmpty() && stk.peek() == popped[i]) {
stk.pop();
++j;
++i;
}
}
return j == pushed.length;
return i == popped.length;
}
}
```
Expand All @@ -102,15 +107,15 @@ class Solution {
public:
bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
stack<int> stk;
int j = 0;
for (int v : pushed) {
stk.push(v);
while (!stk.empty() && stk.top() == popped[j]) {
int i = 0;
for (int x : pushed) {
stk.push(x);
while (stk.size() && stk.top() == popped[i]) {
stk.pop();
++j;
++i;
}
}
return j == pushed.size();
return i == popped.size();
}
};
```
Expand All @@ -120,32 +125,32 @@ public:
```go
func validateStackSequences(pushed []int, popped []int) bool {
stk := []int{}
j := 0
for _, v := range pushed {
stk = append(stk, v)
for len(stk) > 0 && stk[len(stk)-1] == popped[j] {
i := 0
for _, x := range pushed {
stk = append(stk, x)
for len(stk) > 0 && stk[len(stk)-1] == popped[i] {
stk = stk[:len(stk)-1]
j++
i++
}
}
return j == len(pushed)
return i == len(popped)
}
```

#### TypeScript

```ts
function validateStackSequences(pushed: number[], popped: number[]): boolean {
const stk = [];
let j = 0;
for (const v of pushed) {
stk.push(v);
while (stk.length && stk[stk.length - 1] == popped[j]) {
const stk: number[] = [];
let i = 0;
for (const x of pushed) {
stk.push(x);
while (stk.length && stk.at(-1)! === popped[i]) {
stk.pop();
++j;
i++;
}
}
return j == pushed.length;
return i === popped.length;
}
```

Expand All @@ -154,16 +159,16 @@ function validateStackSequences(pushed: number[], popped: number[]): boolean {
```rust
impl Solution {
pub fn validate_stack_sequences(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
let mut stack = Vec::new();
let mut stk: Vec<i32> = Vec::new();
let mut i = 0;
for &num in pushed.iter() {
stack.push(num);
while !stack.is_empty() && *stack.last().unwrap() == popped[i] {
stack.pop();
for &x in &pushed {
stk.push(x);
while !stk.is_empty() && *stk.last().unwrap() == popped[i] {
stk.pop();
i += 1;
}
}
stack.len() == 0
i == popped.len()
}
}
```
Expand All @@ -177,16 +182,16 @@ impl Solution {
* @return {boolean}
*/
var validateStackSequences = function (pushed, popped) {
let stk = [];
let j = 0;
for (const v of pushed) {
stk.push(v);
while (stk.length && stk[stk.length - 1] == popped[j]) {
const stk = [];
let i = 0;
for (const x of pushed) {
stk.push(x);
while (stk.length && stk.at(-1) === popped[i]) {
stk.pop();
++j;
i++;
}
}
return j == pushed.length;
return i === popped.length;
};
```

Expand All @@ -196,16 +201,17 @@ var validateStackSequences = function (pushed, popped) {
public class Solution {
public bool ValidateStackSequences(int[] pushed, int[] popped) {
Stack<int> stk = new Stack<int>();
int j = 0;
foreach (int x in pushed)
{
int i = 0;

foreach (int x in pushed) {
stk.Push(x);
while (stk.Count != 0 && stk.Peek() == popped[j]) {
while (stk.Count > 0 && stk.Peek() == popped[i]) {
stk.Pop();
++j;
i++;
}
}
return stk.Count == 0;

return i == popped.Length;
}
}
```
Expand Down
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