HDU 3347 Calculate the expression By Assassin 模拟水题

题目大意

You may find it’s easy to calculate the expression such as: a = 3 b = 4 c = 5 a + b + c = ? Isn’t it? 

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Input

The first line contains an integer stands for the number of test cases.    Each test case start with an integer n stands for n expressions will follow for this case.Then n – 1 expressions in the format: [variable name][space][=][space][integer] will follow.You may suppose the variable name will only contain lowercase letters and the length will not exceed 20, and the integer will between -65536 and 65536.The last line will contain the expression you need to work out.In the format: [variable name| integer][space][+|-][space][variable name| integer] …= ?You may suppose the variable name must have been defined in the n – 1 expression and the integer is also between -65536 and 65536. You can get more information from the sample.

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Output

For each case, output the result of the last expression.

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Sample Input

34aa = 1bb = -1aa = 2aa + bb + 11 = ?11 + 1 = ?11 + -1 = ?

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Sample Output

1220

题目分析

乍一看挺难，但是注意看题！！！前n-1行格式是固定的，一定是给变量赋值，最后一行就是变量+常数的加减，比较简单，注意每次考虑运算的符号即可。变量可以用 map记录

（开始把题目想太复杂了，所以记录一下简单的做法）

#include<bits/stdc++.h>using namespace std;map<string,int>mp;int string_to_int(string s){        //字符串     int sum=0,pos=0,sign=0;    if(s[pos]=='-'){        sign=1;        pos++;    }    for(;pos<s.size();pos++){        sum=sum*10+s[pos]-'0';    }    if(sign==1){        return -sum;    }    else {        return sum;    }}int main(){    int t,n;    string variablename,c,integer;    scanf("%d",&t);    while(t--){        scanf("%d",&n);        mp.clear();        for(int i=1;i<n;i++){            cin>>variablename>>c>>integer;            mp[variablename]=string_to_int(integer);        }        int sign=0;        long long ans=0;        while(cin>>c){            if(c.size()==1){                if(c[0]=='-'){                    sign=1;                    continue;                }                else if(c[0]=='+'){                    sign=0;                    continue;                }            }            if(c[0]=='=')continue;            if(c[0]=='?')break;            if(c[0]>='a'&&c[0]<='z'){                if(sign==1){                    ans-=mp[c];                }                else {                    ans+=mp[c];                }            }             else {                if(sign==1){                    ans-=string_to_int(c);                }                else {                    ans+=string_to_int(c);                }            }        }        cout<<ans<<endl;    }    return 0; }