UVA - 11954 Very Simple Calculator 【模拟】

题意
模拟二进制数字的位运算

思路
手写 位运算函数
要注意几个坑点
一元运算符的优先级 大于 二元
一元运算符 运算的时候 要取消前导0
二元运算符 运算的时候 要将两个数字 数位补齐
输出的时候 也要 注意 要取消前导0

特别要注意
如果输入的算式 只有一个数字
那么要将 这个数字的前导0 取消 再输出

AC代码

#include <cstdio>
#include <cstring>
#include <ctype.h>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <map>
#include <stack>
#include <set>
#include <numeric>
#include <sstream>
#include <iomanip>
#include <limits>

#define CLR(a) memset(a, 0, sizeof(a))
#define pb push_back

using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef pair<string, int> psi;
typedef pair<string, string> pss;

const double PI = acos(-1.0);
const double E = exp(1.0);
const double eps = 1e-30;

const int INF = 0x3f3f3f3f;
const int maxn = 4e5 + 5;
const int MOD = 1e9 + 7;

string Not(string s)
{
    while (s.size() > 1 && s[0] == '0')
        s.erase(0, 1);
    int len = s.size();
    map <char, char> m;
    m['0'] = '1';
    m['1'] = '0';
    string ans = "";
    for (int i = 0; i < len; i++)
        ans += m[s[i]];
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

string Shr (string s)
{
    while (s.size() > 1 && s[0] == '0')
        s.erase(0, 1);
    string ans = s;
    if (ans.size() == 1)
        return "0";
    if (ans.size() > 1)
        ans.erase(ans.size() - 1, 1);
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

string Shl (string s)
{
    while (s.size() > 1 && s[0] == '0')
        s.erase(0, 1);
    string ans = s;
    ans.insert(ans.size(), "0");
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

string Xor (string x, string y)
{
    string ans = "";
    while (x.size() < y.size())
        x.insert(0, "0");
    while (x.size() > y.size())
        y.insert(0, "0");
    int len = x.size();
    for (int i = 0; i < len; i++)
    {
        if (x[i] != y[i])
            ans += "1";
        else 
            ans += "0";
    }
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

string And (string x, string y)
{
    string ans = "";
    while (x.size() < y.size())
        x.insert(0, "0");
    while (x.size() > y.size())
        y.insert(0, "0");
    int len = x.size();
    for (int i = 0; i < len; i++)
    {
        if (x[i] == '0' || y[i] == '0')
            ans += '0';
        else
            ans += '1';
    }
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

string Or(string x, string y)
{
    string ans = "";
    while (x.size() < y.size())
        x.insert(0, "0");
    while (x.size() > y.size())
        y.insert(0, "0");
    int len = x.size();
    for (int i = 0; i < len; i++)
    {
        if (x[i] == '1' || y[i] == '1')
            ans += '1';
        else
            ans += '0';
    }
    while (ans.size() > 1 && ans[0] == '0')
        ans.erase(0, 1);
    return ans;
}

int main()
{
    int t;
    cin >> t;
    getchar();
    int count = 1;
    while (t--)
    {
        string s;
        getline(cin, s);
        stack <string> code;
        stack <string> num;
        string temp = "";
        int len = s.size();
        for (int i = 0; i <= len; i++)
        {
            if (i < len && s[i] != ' ')
                temp += s[i];
            else
            {
                if (isdigit(temp[0]))
                {
                    string n = temp;
                    num.push(n);
                    if (num.size() >= 1)
                    {
                        n = num.top();
                        num.pop();
                        string s = " ";
                        if (!code.empty())
                            s = code.top();
                        while (s == "not" || s == "shr" || s == "shl")
                        {
                            code.pop();
                            if (s == "not")
                                n = Not(n);
                            else if (s == "shr")
                                n = Shr(n);
                            else if (s == "shl")
                                n = Shl(n);
                            if (!code.empty())
                                s = code.top();
                            else
                                s = " ";
                        }
                        num.push(n);
                    }
                    if (num.size() >= 2)
                    {
                        string s = " ";
                        if (!code.empty())
                            s = code.top();
                        while ((s == "xor" || s == "and" || s == "or") && num.size() >= 2)
                        {
                            code.pop();
                            string x = num.top();
                            num.pop();
                            string y = num.top();
                            num.pop();
                            string ans;
                            if (s == "xor")
                                ans = Xor(x, y);
                            else if (s == "and")
                                ans = And(x, y);
                            else if (s == "or")
                                ans = Or(x, y);
                            if (!code.empty())
                                s = code.top();
                            else
                                s = " ";
                            num.push(ans);
                        }
                    }
                }
                else
                {
                    code.push(temp);
                }
                temp.clear();
            }
        }
        string ans = num.top();
        while (ans.size() > 1 && ans[0] == '0')
            ans.erase(0, 1);
        printf("Case %d: ", count++);
        cout << ans << endl;
    }
}