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9/28/20

Watermelon codechef lunchtime Problem solution with explanation| September Lunchtime

 Watermelon codechef lunchtime Problem solution with explanation| September Lunchtime-




Problem Statement-

Let's call a sequence good if the sum of all its elements is 0.

You have a sequence of integers A1,A2,,AN. You may perform any number of operations on this sequence (including zero). In one operation, you should choose a valid index i and decrease Ai by i. Can you make the sequence good using these operations?

Input

  • The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
  • The first line of each test case contains a single integer N.
  • The second line contains N space-separated integers A1,A2,,AN.

Output

For each test case, print a single line containing the string "YES" if it is possible to make the given sequence good or "NO" if it is impossible.

Constraints

  • 1T1,000
  • 1N10
  • |Ai|100 for each valid i

Subtasks

Subtask #1 (10 points): N=1

Subtask #2 (30 points): N2

Subtask #3 (60 points): original constraints

Example Input

2
1
-1
2
1 2

Example Output

NO
YES

Explanation

Example case 2: We can perform two operations ― subtract 1 from A1 and 2 from A2.

link of Problem->https://www.codechef.com/LTIME88B/problems/WATMELON

Watermelon codechef lunchtime Problem solution with explanation| September Lunchtime



Watermelon CodeChef lunchtime Problem solution->


This Problem is the easiest problem of this contest. Read carefully the problem as mentioned in the problem 
the sequence good if the sum of all its elements is 0.
So first of all add all the elements of the given array.
There can be 3 cases

1-if the sum is 0 then we need to do nothing we have to print :YES

2- is sum is less then 0 - if the sum of all the element is less then 0 we  never make this array good because i (index) is always positive and subtracting a positive number from a negative number gives us more negative number so in this case we have to print "NO";

3- if sum is grater then 0. read problem care fully it is mentioned in the problem that 
You may perform any number of operations on this sequence (including zero).

means you we can subtract i any number of time.

but we know that we will always have i=1 that is first index and every number is multiple of 1 so we can generate 0 by subtracting 1 any number of times so the conclusion is if the sum is  grater then 0 ans is always "YES" because we can generate 0 by subtracting 1 any number of time.

here we need a little observation for this question. 

complete code of the problem 








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