946:验证栈序列

LeetCode/src/main/java/leetcode/editor/cn/ValidateStackSequences.java

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+//给定 pushed 和 popped 两个序列，每个序列中的 值都不重复，只有当它们可能是在最初空栈上进行的推入 push 和弹出 pop 操作序列的结果时
+//，返回 true；否则，返回 false 。 
+//
+// 
+//
+// 示例 1： 
+//
+// 输入：pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
+//输出：true
+//解释：我们可以按以下顺序执行：
+//push(1), push(2), push(3), push(4), pop() -> 4,
+//push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1
+// 
+//
+// 示例 2： 
+//
+// 输入：pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
+//输出：false
+//解释：1 不能在 2 之前弹出。
+// 
+//
+// 
+//
+// 提示： 
+//
+// 
+// 0 <= pushed.length == popped.length <= 1000 
+// 0 <= pushed[i], popped[i] < 1000 
+// pushed 是 popped 的排列。 
+// 
+// Related Topics 栈 
+// 👍 175 👎 0
+
+package leetcode.editor.cn;
+
+import java.util.Stack;
+
+//946:验证栈序列
+public class ValidateStackSequences {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new ValidateStackSequences().new Solution();
+        //true
+        System.out.println(solution.validateStackSequences(new int[]{1, 2, 3, 4, 5}, new int[]{4, 5, 3, 2, 1}));
+        //false
+        System.out.println(solution.validateStackSequences(new int[]{1, 2, 3, 4, 5}, new int[]{4, 3, 5, 1, 2}));
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public boolean validateStackSequences(int[] pushed, int[] popped) {
+            Stack<Integer> stack = new Stack<>();
+            int j = 0;
+            for (int i = 0; i < popped.length; i++) {
+                if (j == pushed.length) {
+                    return false;
+                }
+                while (j < pushed.length && popped[i] != pushed[j]) {
+                    stack.push(pushed[j]);
+                    j++;
+                    if (j == pushed.length) {
+                        return false;
+                    }
+                }
+                j++;
+                while (!stack.isEmpty() && i < popped.length - 1 && popped[i + 1] == stack.peek()) {
+                    stack.pop();
+                    i++;
+                }
+            }
+            return true;
+//            // 官方
+//            int N = pushed.length;
+//            Stack<Integer> stack = new Stack<>();
+//
+//            int j = 0;
+//            for (int x : pushed) {
+//                stack.push(x);
+//                while (!stack.isEmpty() && j < N && stack.peek() == popped[j]) {
+//                    stack.pop();
+//                    j++;
+//                }
+//            }
+//
+//            return j == N;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

LeetCode/src/main/java/leetcode/editor/cn/ValidateStackSequences.md

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+<p>给定&nbsp;<code>pushed</code>&nbsp;和&nbsp;<code>popped</code>&nbsp;两个序列，每个序列中的 <strong>值都不重复</strong>，只有当它们可能是在最初空栈上进行的推入 push 和弹出 pop 操作序列的结果时，返回 <code>true</code>；否则，返回 <code>false</code>&nbsp;。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre><strong>输入：</strong>pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
+<strong>输出：</strong>true
+<strong>解释：</strong>我们可以按以下顺序执行：
+push(1), push(2), push(3), push(4), pop() -&gt; 4,
+push(5), pop() -&gt; 5, pop() -&gt; 3, pop() -&gt; 2, pop() -&gt; 1
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre><strong>输入：</strong>pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
+<strong>输出：</strong>false
+<strong>解释：</strong>1 不能在 2 之前弹出。
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ol>
+	<li><code>0 &lt;= pushed.length == popped.length &lt;= 1000</code></li>
+	<li><code>0 &lt;= pushed[i], popped[i] &lt; 1000</code></li>
+	<li><code>pushed</code>&nbsp;是&nbsp;<code>popped</code>&nbsp;的排列。</li>
+</ol>
+<div><div>Related Topics</div><div><li>栈</li></div></div>\n<div><li>👍 175</li><li>👎 0</li></div>