leetcode: Add 0946

src/leetcode/0946.validate-stack-sequences/Cargo.toml

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+[package]
+name = "lc-0946-validate-stack-sequences"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

src/leetcode/0946.validate-stack-sequences/index.md

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+
+# 
+
+[问题描述](../problems/)

src/leetcode/0946.validate-stack-sequences/src/main.rs

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+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+// Stack
+pub fn validate_stack_sequences1(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
+    assert_eq!(pushed.len(), popped.len());
+    assert!(!pushed.is_empty());
+
+    let mut stack: Vec<i32> = Vec::new();
+    let mut pop_index: usize = 0;
+
+    // 先遍历 pushed 数组.
+    for num in &pushed {
+        // 如果与 popped 当前元素相等, 则不必入栈, 直接将 popped 的索引移到下一位.
+        if Some(num) == popped.get(pop_index) {
+            pop_index += 1;
+
+            // 贪心, 检查栈中剩下的元素, 能不能被出栈.
+            while pop_index < popped.len() && !stack.is_empty() {
+                if popped.get(pop_index) == stack.last() {
+                    // 相等则出栈, 同时移动索引.
+                    pop_index += 1;
+                    let _ = stack.pop();
+                } else {
+                    // 不相等, 则立即中止循环.
+                    break;
+                }
+            }
+        } else {
+            // 如果不相等, 则入栈.
+            stack.push(*num);
+        }
+    }
+
+    // 遍历 popped 数组中剩下的元素, 看它们与出栈后的元素是否相等.
+    while pop_index < popped.len() {
+        // 比较popped 中的元素与栈顶元素是否相等
+        if popped.get(pop_index) != stack.pop().as_ref() {
+            return false;
+        }
+        pop_index += 1;
+    }
+
+    stack.is_empty()
+}
+
+// Stack
+// 优化栈的操作, 遍历 popped 数组.
+pub fn validate_stack_sequences2(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
+    assert_eq!(pushed.len(), popped.len());
+    assert!(!pushed.is_empty());
+
+    let mut stack: Vec<i32> = Vec::with_capacity(pushed.len());
+    let mut push_iter = pushed.into_iter();
+
+    // 先遍历 popped 数组.
+    for pop_num in &popped {
+        // 如果当前的栈顶与当前的 pop_num 不相等, 则有必要再入栈一些新的整数.
+        while Some(pop_num) != stack.last() {
+            if let Some(push_num) = push_iter.next() {
+                // 入栈
+                stack.push(push_num);
+            } else {
+                // 如果所有元素都已经入栈, 仍然找不到相等的元素可以出栈, 那就说明 popped
+                // 不是一个有效的出栈序列.
+                return false;
+            }
+        }
+        // pop_num 与栈顶相等, 可以出栈了.
+        let _stack_pop = stack.pop();
+    }
+    true
+}
+
+pub type SolutionFn = fn(Vec<i32>, Vec<i32>) -> bool;
+
+fn check_solution(func: SolutionFn) {
+    let pushed = vec![1, 2, 3, 4, 5];
+    let popped = vec![4, 5, 3, 2, 1];
+    assert!(func(pushed, popped));
+
+    let pushed = vec![1, 2, 3, 4, 5];
+    let popped = vec![4, 3, 5, 1, 2];
+    assert!(!func(pushed, popped));
+
+    let pushed = vec![2, 1, 0];
+    let popped = vec![1, 2, 0];
+    assert!(func(pushed, popped));
+}
+
+fn main() {
+    check_solution(validate_stack_sequences1);
+    check_solution(validate_stack_sequences2);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{check_solution, validate_stack_sequences1, validate_stack_sequences2};
+
+    #[test]
+    fn test_validate_stack_sequences1() {
+        check_solution(validate_stack_sequences1);
+    }
+
+    #[test]
+    fn test_validate_stack_sequences2() {
+        check_solution(validate_stack_sequences2);
+    }
+}