uva 112 - Tree Summing

来源：互联网发布：公主坟软件培训编辑：程序博客网时间：2024/05/22 15:07

wa了两次，就是少了负数和0（）的情况。。。。

#include <iostream>#include <cstdio>#include <cstring>#include <iterator>#include <cmath>#include <algorithm>#include <stack>using namespace std;stack<char> s;stack<int> num;int n, flag, ok;char ch;void dfs(int sum){    if(ch == '(')    {        flag++;        s.push(ch);        int a = 0;        int fushu = 0;        while(cin >> ch)        {            if(ch == '-')            {                fushu = 1;                continue;            }            if(isdigit(ch))                a = a*10 + ch-'0';            else break;        }        if(fushu)            a = -a;        if(ch == ')')        {            flag++;            s.pop();            if(flag == 4)                if(sum == n)                    ok++;            if(s.empty())                return;            cin >> ch;            dfs(sum);        }        else        {            flag = 0;            sum+=a;            num.push(a);            dfs(sum);        }    }    else if(ch == ')')    {        flag = 0;        s.pop();        if(s.empty())            return;        else        {            cin >> ch;            int mark = num.top();            num.pop();            dfs(sum-mark);        }    }}int main(){    while(cin >> n)    {        ok = 0;        flag = 0;        cin >> ch;        dfs(0);        if(ok)            cout << "yes" << endl;        else            cout << "no" << endl;    }    return 0;}