C*++ Calculations

http://codeforces.com/problemset/problem/39/A

贪心 按照常数大小从小到大排序， 结果一个一个计算上来， 不影响结果正确性。

#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <fstream>
#include <string>
#include <cstring>
#include <algorithm>

int f_min(int x,int y) {if(x<y)return x; else return y;}
int f_max(int x,int y) {if(x<y)return y; else return x;}
void swap(int&x,int&y) {x=x^y;y=x^y;x=x^y;}
int f_abs(int x) {return (x)>(0)?(x):(-x);}
int lowbit(int x) {return (x)&(-x);}
bool isdig(char ch) {return ch>='0' && ch<='9';}
//double f_min(double x,double y) {if(x<y)return x; else return y;}
//double f_max(double x,double y) {if(x<y)return y; else return x;}
using namespace std;

const int MM = 222222;
#define mod 10000000000
const double Pi = acos(-1.0);
const double lep = 1e-10;
const double inf = 1000000000.00;
#define debug puts("wrong")
#define maxint 0x3f3f3f3f
#define lson rt<<1
#define rson rt<<1|1
typedef __int64 int64;
//typedef long long int64;
//const __int64 maxint = 1000000000000000;
int dx[8]={1,2,1,2,-1,-2,-1,-2};
int dy[8]={2,1,-2,-1,2,1,-2,-1};


int N,M, Q;
int NE;
struct Pos {
    int64 val;
    bool ff;
    bool  operator<(Pos x) const{
        return val<x.val;
    }
}p[MM];

char name[MM];

void get_data() {
    int64 i,j,k,a,tmp,len;
    scanf("%s",name);
    len=strlen(name);
    NE=0;
    for(i=0;i<len;i++) {
//        printf("%d\n", i);
        if(i==0) {
            if(name[i]=='a') {
                p[NE].val=1;
                p[NE++].str="a";
                i+=2;
                continue;
            }
            if(name[i]=='+') {
                p[NE].val=1;
                p[NE++].str="+";
                i+=2;
                continue;
            }
            if(isdig(name[i])) {
                tmp=0;
                for(j=i;j<len;j++) 
                    if(name[j]=='*') break;
                    else tmp=tmp*10+name[j]-'0';;
                p[NE].val=tmp; p[NE++].str=name[j+1];
                i=j+3;
                continue;
            }
        }
        else {
            if(name[i]=='+') {
                if(name[i+1]=='a') {
                 p[NE].val=1;
                 p[NE++].str="a";
                 i+=3;
                 continue;
                }
                if(isdig(name[i+1])) {
                    tmp=0;
                    for(j=i+1;j<len;j++) 
                        if(name[j]=='*') break;
                        else tmp=tmp*10+name[j]-'0';
                    p[NE].val=tmp; p[NE++].str=name[j+1];
                    i=j+3;
                    continue;
                }
                if(name[i+1]=='+') {
                    p[NE].val=1;
                    p[NE++].str="+";
                    i+=3;
                    continue;
                }
            }
            if(name[i]=='-') {
                    if(name[i+1]=='a') {
                        p[NE].val=-1; 
                        p[NE++].str=name[i+1];
                        i+=3;
                        continue;
                    }
                    if(isdig(name[i+1])) {
                        tmp=0;
                        for(j=i+1;j<len;j++) 
                            if(name[j]=='*') break;
                            else tmp=tmp*10+name[j]-'0';
                        p[NE].val=-tmp; p[NE++].str=name[j+1];
                        i=j+3;
                        continue;
                    }
                    if(name[i+1]=='+') {
                        p[NE].val=-1; 
                        p[NE++].str=name[i+1];
                    i+=3;
                    continue;
                }    
        }
    }
    }
}
void solve() {
    int64 i,j,k,tmp=0,ans=0;
    sort(p,p+NE);
//    for(i=0;i<NE;i++) cout<<p[i].str<<endl;
    for(i=0;i<NE;i++) {
        if(p[i].str=="+") ans+=(p[i].val*(N+1));
        else ans+=(p[i].val*N);
        N++;
    }
    printf("%I64d\n", ans);
}

int main() {
    //    freopen("input.txt","r",stdin);
    //    freopen("output.txt","w",stdout);
    while(scanf("%I64d",&N)!=EOF) get_data(),solve();
    return 0;
}
/*
10
a++-++a-5*++a-4*a++
*/