A - Soldier and Bananas
Time Limit:1000MS Memory Limit:262144KB 64bit IO Format:%I64d & %I64u
Description
A soldier wants to buy w bananas in the shop. He has to pay k dollars for the first banana, 2k dollars for the second one and so on (in other words, he has to pay i·k dollars for the i-th banana).
He has n dollars. How many dollars does he have to borrow from his friend soldier to buy w bananas?
Input
The first line contains three positive integers k, n, w (1 ≤ k, w ≤ 1000, 0 ≤ n ≤ 109), the cost of the first banana, initial number of dollars the soldier has and number of bananas he wants.
Output
Output one integer — the amount of dollars that the soldier must borrow from his friend. If he doesn't have to borrow money, output 0.
Sample Input
Input3 17 4Output13
题意:
士兵去买香蕉,买的第一根香蕉的价格为k,第i根的价格为i*k。给定士兵带的钱和需要买的香蕉数目,求士兵要借多少钱,如果不用借钱,则输出0.(由于没有判断输出0的条件WA了一发..冤枉啊!!!!!)
虽然是一道水题,但还是发出来劝解各位小伙伴和自己一定要认真读题,千万不要冤WA。
还是附AC代码:
1 #include<iostream> 2 using namespace std; 3 4 int a[1001]; 5 6 int main(){ 7 int k,n,w,sum=0; 8 cin>>k>>n>>w; 9 for(int i=1;i<=w;i++){ 10 a[i]=i*k; 11 sum+=a[i]; 12 } 13 if(sum-n>0)//!!!!!! 14 cout<<sum-n<<endl; 15 else 16 cout<<"0"<<endl; 17 return 0; 18 }