CCF認證 201612-2：工資計算（C++）(90分)

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
int main()
{
	int s,a,i;
	double sum=0;
	cin>>s;
	if(s<=3500){
		cout<<s;
	}else{
		for(i=s;;i++){
			a=i-3500;
			if(a<1500){
				sum=a*0.03;
			}else if(a<4500){
				sum=1500*0.03+(a-1500)*0.1;
			}else if(a<9000){
				sum=1500*0.03+(4500-1500)*0.1+(a-4500)*0.2;
			}else if(a<35000){
				sum=1500*0.03+(4500-1500)*0.1+(9000-4500)*0.2+(a-9000)*0.25;
			}else if(a<55000){
				sum=1500*0.03+(4500-1500)*0.1+(9000-4500)*0.2+(35000-9000)*0.25+(a-35000)*0.3;
			}else if(a<80000){
				sum=1500*0.03+(4500-1500)*0.1+(9000-4500)*0.2+(35000-9000)*0.25+(55000-35000)*0.3+(a-55000)*0.35;
			}else if(a>=80000){
				sum=1500*0.03+(4500-1500)*0.1+(9000-4500)*0.2+(35000-9000)*0.25+(55000-35000)*0.3+(80000-55000)*0.35+(a-80000)*0.45;
			}
			if(sum+s==i){
				cout<<i; 
				break;
			}
		}
	}
	return 0;
}