TJU训练赛—L

4171.    L-The math problem

Time Limit: 1.0 Seconds    Memory Limit: 65536K

Total Runs: 286   

Accepted Runs: 86

Given an array a with n intergers, please tell me the max(aj−ai),0≤i≤j≤n−1 max(aj−ai),0≤i≤j≤n−1.

Input

The input consists of multiple test cases. The first line contains an integer T T, indicating the number of test cases.(1≤T≤1000) (1≤T≤1000)
Each case contains one integer N N.(0≤N≤107) (0≤N≤107). Then comes a line with N intergers ai(−107≤ai≤107) ai(−107≤ai≤107)

Output

For each case only output the answer. 

Sample Input

1
5
1 3 5 4 2

Sample Output

4

【分析】

送分题....求这组序列中最大的a[j]-a[i]，保证j>=i

因为j可以等于i所以最小值不会是负数，然后注意下只能用后面的数减去前面的数，所以不能求序列最大值和最小值减一下...

求一下1-i的最小值然后用当前读取的x-min跟ans判断一下求个max就好了

【代码】

#include <stdio.h>
int main()
{
  int pp;scanf("%d",&pp);
  while (pp--)
  {
    int n;scanf("%d",&n);
    int now,x;scanf("%d",&now);
    int ans=0;
    for (int i=1;i<n;i++)
    {
      scanf("%d",&x);
      if (x-now>ans) ans=x-now;
      if (x<now) now=x; 
    }
    printf("%d\n",ans);
  }
  return 0;  
}