LeetCode 1441. 用栈操作构建数组

1441. 用栈操作构建数组

【分析】因为保证了顺序是从小到大，所以直接枚举target中的元素，和[1, n]的元素，如果相同，压入Push，否则压入Push和Pop。

class Solution {

    // 栈

    public List<String> buildArray(int[] target, int n) {
        int j = 1;
        List<String> ans = new ArrayList();
        for (int i = 0; i < target.length; i++) {
            while (j != target[i]) {
                ans.add("Push");
                ans.add("Pop");
                j++;
            }
            ans.add("Push");
            j++;
        }
        return ans;
    }
}

class Solution {
public:
    vector<string> buildArray(vector<int>& target, int n) {
        vector<string> ans;
        int j = 1;
        for (int i = 0; i < target.size(); i++) {
            while (j != target[i]) {
                j++;
                ans.push_back("Push");
                ans.push_back("Pop");
            }
            ans.push_back("Push");
            j++;
        }
        return ans;
    }
};