LeetCode（剑指 Offer）- 31. 栈的压入弹出序列

Posted 2022-12-05 放羊的牧码

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题目大意：略

解题思路：略

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AC 代码

• Java

// 解决方案(1)
class Solution 
    public boolean validateStackSequences(int[] pushed, int[] popped) 
		int[] stack = new int[pushed.length];
		for (int i = 0, j = 0, top = -1; i < popped.length; i++) 
			boolean flag = false;
			int pop = popped[i];
			if (top != -1 && stack[top] == pop) 
				top--;
				flag = true;
			 else 
				while (j < pushed.length) 
					if (pushed[j] == pop) 
						j++;
						flag = true;
						break;
					
					stack[++top] = pushed[j++];
				
			

			if (!flag) 
				return false;
			
		
		return true;
	


// 解决方案(2)
class Solution 
    public boolean validateStackSequences(int[] pushed, int[] popped) 
        Stack<Integer> stack = new Stack<>();
        int i = 0;
        for(int num : pushed) 
            stack.push(num); // num 入栈
            while(!stack.isEmpty() && stack.peek() == popped[i])  // 循环判断与出栈
                stack.pop();
                i++;
            
        
        return stack.isEmpty();
    

• C++

class Solution 
public:
    bool validateStackSequences(vector<int>& pushed, vector<int>& popped) 
        stack<int> stk;
        int i = 0;
        for(int num : pushed) 
            stk.push(num); // num 入栈
            while(!stk.empty() && stk.top() == popped[i])  // 循环判断与出栈
                stk.pop();
                i++;
            
        
        return stk.empty();
    
;