BUAA 623 Chem is Try！

http://oj55.bianchengla.com/problem/623/

　　好久没写过题解了，昨天做了一道挺恶心的题目，贴一下代码上来。看了一下提交状况，好像我的代码挺短的了，至少我找不到比我短的代码。RE1，AC。

代码如下：

#include <cctype>
#include <cstdio>
#include <cstring>
#include <map>
#include <string>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 111111;
char buf[N], *p[2];
typedef long long LL;
typedef map<string, LL> MSL;
#define x first
#define y second

string get_s(int x) {
    string ret = "";
    ret += *(p[x]++);
    while (islower(*p[x])) ret += *p[x], p[x]++;
    return ret;
}

int get_d(int x) {
    int ret = 0;
    while (isdigit(*p[x])) ret = ret * 10 + *p[x] - '0', p[x]++;
    return ret;
}

MSL merge(MSL a, MSL b) {
    MSL c;
    for (MSL::iterator mi = a.begin(); mi != a.end(); mi++) c[mi->x] += mi->y;
    for (MSL::iterator mi = b.begin(); mi != b.end(); mi++) c[mi->x] += mi->y;
    return c;
}


void print(MSL &a) { for (MSL::iterator mi = a.begin(); mi != a.end(); mi++) cout << mi->x << '~' << mi->y << ' '; cout << endl; }
void multiply(MSL &a, LL p) { for (MSL::iterator mi = a.begin(); mi != a.end(); mi++) mi->y *= p; }

MSL dfs(int x, char end) {
    MSL cur;
    //cout << x << ' ' << p[x] << endl;
    while (*p[x] && *p[x] != end && *p[x] != ')') {
        //cout << x << ' ' << *p[x] << endl;
        if (*p[x] == '+') { p[x]++; continue; }
        if (isdigit(*p[x])) {
            int t = get_d(x);
            MSL tmp = dfs(x, '+');
            multiply(tmp, t);
            cur = merge(cur, tmp);
        } else {
            if (*p[x] == '(') {
                p[x]++; MSL tmp = dfs(x, ')');
                if (*p[x] == ')') p[x]++;
                if (isdigit(*p[x])) multiply(tmp, get_d(x));
                cur = merge(cur, tmp);
            } else {
                string s = get_s(x);
                if (isdigit(*p[x])) cur[s] += get_d(x);
                else cur[s]++;
            }
        }
    }
    return cur;
}

int main() {
    //freopen("in", "r", stdin);
    while (~scanf("%s", buf)) {
        p[0] = p[1] = buf;
        while (*p[1] != '=') p[1]++; *(p[1]++) = 0;
        MSL ans1, ans2, tmp;
        while (1) {
            tmp = dfs(0, '+');
            ans1 = merge(ans1, tmp);
            if (*p[0] == 0) break;
            p[0]++;
            //cout << p[0] << endl;
        }
        while (1) {
            tmp = dfs(1, '+');
            ans2 = merge(ans2, tmp);
            if (*p[1] == 0) break;
            p[1]++;
            //cout << p[1] << endl;
        }
        MSL::iterator m1 = ans1.begin(), m2 = ans2.begin();
        //print(ans1); print(ans2);
        while (1) {
            if (m1 == ans1.end()) break;
            if (m2 == ans2.end()) break;
            if (*m1 != *m2) break;
            m1++, m2++;
        }
        m1 == ans1.end() && m2 == ans2.end() ? puts("YES") : puts("NO");
    }
    return 0;
}

——written by Lyon