题目描述

blablabla

样例

blablabla

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

#include <bits/stdc++.h>
#include <iostream>

using namespace std;

stack<int> nums;
stack<char> ops;
stack<string> srs;

string res = "";


void cal()
{
    string v = "";
    int a = nums.top(); nums.pop();
    string b = srs.top(); srs.pop();


    while(a --) v += b;

    srs.push(v); 

    if(srs.size() > 1)
    {
        res = srs.top();
        srs.pop();
        res = srs.top() + res;
        srs.pop();
        srs.push(res);
    }
}

int main()
{
    string s;
    cin >> s;

    for(int i = 0; i < s.size(); i ++)
    {
        char c = s[i];
        if(c >= '0' && c <= '9')
        {
            int j = i, v = 0;
            while(j < s.size() && s[j] >= '0' && s[j] <= '9')
            {
                v = v * 10 + s[j] - '0';
                j ++;
            } 
            i = j - 1;
            nums.push(v);
        }
        else if(c == '[')
        {
            ops.push(c);
        }

        else if(c == ']')
        {
            if(ops.top() == '[') cal();
            ops.pop();
        }

        else if(c >= 'a' && c <= 'z')
        {
            int k = i;
            string sr = "";
            while(k < s.size() && s[k] >= 'a' && s[k] <= 'z')
            {
                sr = sr + s[k];
                //sr = s[j] + sr;
                k ++;
            }
            i = k - 1;
            srs.push(sr);
        }
    }

    if(srs.size() > 1)
    {
        string srt = srs.top();
        srs.pop();
        srt = srs.top() + srt;
        srs.push(srt);
    }
    cout << srs.top() << endl;
    return 0;
}

算法2

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla