# Another Training Contest

**酱油**posted @ Sat, 08 Aug 2015 13:17:47 +0800 in OI life with tags NOIP 2015 Training Contest , 399 readers

Aug. 8th, 2015

An NOIP2015 Training Contest Prepared by hhw && mxh1999

A very tough contest, right?

Time: 8:00 a.m. ~ 11:30 a.m.

Number of Prob.s: 3

Result:

I didn't know why I became the last contestant... T_T

A car starts with velocity v1 and ends with velocity v2. The car can change its velocity immediately in the area of ±d. There is t that shows total time the car spends on the road. Then what's the longest distance can the car travel? Input: v1 v2 t d Output: S(indicating the longest distance) Sample Input: 5 6 4 2 Sample Output: 26 Explanations: 5+7+8+6=26 (+2 +1 -2) For all 20 testcases: 1<=v1,v2<=100; 2<=t<=100; 0<=d<=10; It is confirmed that there is only one fixed answer for each of the testcases.

Prob. A was considered as "a bottle of purified water", but I didn't get 100 pts.. In fact I had never realized that until I got the result. Why, only 60 pts.?

After comparing my program with Mars_cat's, I was perfectly shocked! I just made a mistake in searching for the answer, which led to missing of 40 pts. because of WA.

#include <iostream> #include <cstdio> #include <cstdlib> #include <cmath> #include <ctime> #include <cstring> #include <algorithm> #define DONS 1010 using namespace std; int v1,v2,t,d,i,j,sum,f[DONS],g[DONS]; int main() { freopen("trip.in","r",stdin);freopen("trip.out","w",stdout); scanf("%d%d%d%d",&v1,&v2,&t,&d); for(i=1;i<=t;i++){f[i]=v1+(i-1)*d;g[i]=v2+(t-i)*d;} for(i=1;i<=t;i++)if(f[i]-g[i]==0 || (f[i+1]-g[i+1])*(v1-v2)<0)break; for(j=1;j<=t;j++)sum+=min(f[j],g[j]);/*Mistake: for(j=1;j<=i;j++)sum+=f[j];for(j=i+1;j<=t;j++)sum+=g[j];*/ printf("%d\n",sum); fclose(stdin);fclose(stdout);return 0; }

Wondering why I was wrong? Here is an example: (trip8.in)

2 1

2 2

When testing my first version of code, I got WA because my output was 6. But, obviously, the standard answer is 3.

Carelessness led to failure? Now I am sure about that...

Prob. B & Prob. C were difficult. Waiting for discussion to solve.

I am always a WEAK DISH, so I haven't correct the other two programs into std's yet.

Just like my Chinese nickname, participating in the **unscientific** contest is **exactly** "getting a bottle of Soy Sauce".

(Comments are welcomed and it is recommended that you reply in English.)