Openjudge 3342 字符串操作

这以题和括号匹配/逆波兰表达式这种有点像
但是由于返回值不同，需要用用栈+递归联合模拟才好做

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <string>
#include <queue>
#include <stack>

using namespace std;

const int MAX_N = 5010;

int n;

string str[MAX_N];
queue<string> command;
stack<string> que;

inline int toInt(string x) { return atoi(x.c_str()); }

inline bool isDigit(string x) {
    for (int i = 0; i < x.size(); ++i)
        if (x[i] < '0' || x[i] > '9')   return false;
    if (toInt(x) > 99999 || toInt(x) < 0)   return false;
    return true;
}

inline string getCommand() {
    string s = command.front();
    command.pop();
    return s;
}

inline string getTop() {
    string s = que.top();
    que.pop();
    return s;
}

void maintain(string& opr) {
    while (!command.empty()) command.pop();
    opr += " ";
    while (!opr.empty()) {
        int ed = opr.find_first_of(" ");
        command.push(opr.substr(0, ed));
        opr = opr.substr(ed + 1);
    }
}

void solve() {
    string arg = getCommand();
    que.push(arg);
    if (arg == "copy") { 
        solve();
        int n = toInt(getTop());
        solve();
        int x = toInt(getTop());
        solve();
        int l = toInt(getTop());
        que.pop();
        que.push(str[n].substr(x, l));
        return;
    }
    if (arg == "add") {
        solve();
        string s1 = getTop();
        solve();
        string s2 = getTop();
        que.pop();
        if (isDigit(s1) && isDigit(s2))
            que.push(to_string(toInt(s1) + toInt(s2)));
        else
            que.push(s1 + s2);
        return;
    }
    if (arg == "find" || arg == "rfind") {
        solve();
        string s = getTop();
        solve();
        int n = toInt(getTop()), loc;
        que.pop();
        if (arg == "find")
            loc = str[n].find(s);
        else
            loc = str[n].rfind(s);
        if (loc == -1)
            loc = s.length();
        que.push(to_string(loc));
        return;
    }
    if (arg == "insert") {
        solve();
        string s = getTop();
        solve();
        int n = toInt(getTop());
        solve();
        int x = toInt(getTop());
        que.pop();
        str[n].insert(x, s);
        return;
    }
    if (arg == "reset") {
        solve();
        string s = getTop();
        solve();
        int n = toInt(getTop());
        que.pop();
        str[n] = s;
        return;
    }
    if (arg == "print") {
        solve();
        int n = toInt(getTop());
        que.pop();
        cout << str[n] << endl;
        return;
    }
    if (arg == "printall") {
        que.pop();
        for (int i = 1; i <= n; ++i)
            cout << str[i] << endl;
        return;
    }
    return;
}

int main() {

//    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);

    cin >> n;
    for (int i = 1; i <= n; ++i)    cin >> str[i];
    cin.get();

    string opr;
    while (getline(cin, opr)) {
        if (opr == "over")  break;
        maintain(opr);
        solve();
    }

    return 0;
}