算法竞赛入门经典-前四章-UVa10071 - Back to High School Physics-重温高中物理-难度0

题目链接：http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=94&page=show_problem&problem=1012

Problem B

Back to High School Physics

Input: standard input

Output: standard output

 

A particle has initial velocity and constant acceleration. If its velocity after certain time is v then what will its displacement be in twice of that time?

 

Input

The input will contain two integers in each line. Each line makes one set of input. These two integers denote the value of v (-100 <= v <= 100) and t(0<=t<= 200) ( t means at the time the particle gains that velocity) 

 

Output

For each line of input print a single integer in one line denoting the displacement in double of that time.

 

Sample Input

0 0
5 12

Sample Output

0
120

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代码+分析：

/* *分析： 设初始速度为v0，加速度为a则 v0+a*t=v； *现在求s = v0*2*t+1/2*a*(2*t)^2=2*t(v0+a*t)=2*t*v */#include  <iostream>using namespace std;int main(){//freopen("f:\\input.txt", "r", stdin);    int v, t;while(cin >> v >> t){cout << 2 * v * t << endl;}return 0;}