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LeetCode--946. 验证栈序列
给定 pushed 和 popped 两个序列,只有当它们可能是在最初空栈上进行的推入 push 和弹出 pop ...
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05
2018/12

LeetCode--946. 验证栈序列

给定 pushed 和 popped 两个序列,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。

思路:简单模拟

class Solution {
public:
    bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
        stack<int> st;
        int push_i = 0;
        int pop_i = 0;
        int len = pushed.size();
        while(push_i<len){
            int top = pushed[push_i++];
            st.push(top);
            while(!st.empty()){
                int tp = st.top();
                st.pop();
                if(tp==popped[pop_i]){
                    pop_i++;
                }else{
                    st.push(tp);
                    break;
                }
            }
        }
        while(pop_i<len){
            int top = st.top();
            st.pop();
            if(top!=popped[pop_i++])return false;
        }
        
        if(!st.empty())return false;
        return true;
        
    }
};
Last modification:December 5th, 2018 at 10:01 pm
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