## 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 ${A}_{1},{A}_{2},\dots ,{A}_{N}$. You may perform any number of operations on this sequence (including zero). In one operation, you should choose a valid index $i$ and decrease ${A}_{i}$ 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 ${A}_{1},{A}_{2},\dots ,{A}_{N}$.

### 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

• $1\le T\le 1,000$
• $1\le N\le 10$
• $|{A}_{i}|\le 100$ for each valid $i$

Subtask #1 (10 points): $N=1$

Subtask #2 (30 points): $N\le 2$

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 ${A}_{1}$ and $2$ from ${A}_{2}$.

#### 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

### codeforces rating system | Codeforces rating Newbie to Legendary Grandmaster

Codeforces rating system | Codeforces rating Newbie to Legendary Grandmaster- Codeforces is one of the most popular platforms for competitive programmers and  codeforces rating matters a lot  .  Competitive Programming  teaches you to find the easiest solution in the quickest possible way. CP enhances your problem-solving and debugging skills giving you real-time fun. It's brain-sport. As you start solving harder and harder problems in live-contests your analytical and rational thinking intensifies. To have a good codeforces profile makes a good impression on the interviewer. If you have a good  codeforces profile so it is very easy to get a referral for product base company like amazon, google , facebook etc.So in this blog I have explained everything about codeforces rating system. What are different titles on codeforces- based on rating codeforces divide rating into 10 part. Newbie Pupil Specialist Expert Candidate Codemaster Master International Master Grandmaster Internat

### Apple Division CSES Problem Set Solution | CSES Problem Set Solution Apple division with code

Apple Division CSES Problem Set Solution | CSES Problem Set Solution Apple division with code - Apple Division CSES Problem Solution Easy Explanation. Apple division is problem is taken form cses introductory problem set.Let's Read Problem statement first. Problem Statement- Time limit:  1.00 s   Memory limit:  512 MB There are  n n  apples with known weights. Your task is to divide the apples into two groups so that the difference between the weights of the groups is minimal. Input The first input line has an integer  n n : the number of apples. The next line has  n n  integers  p 1 , p 2 , … , p n p 1 , p 2 , … , p n : the weight of each apple. Output Print one integer: the minimum difference between the weights of the groups. Constraints 1 ≤ n ≤ 20 1 ≤ n ≤ 20 1 ≤ p i ≤ 10 9 1 ≤ p i ≤ 10 9 Example Input: 5 3 2 7 4 1 Output: 1 Explanation: Group 1 has weights 2, 3 and 4 (total weight 9), and group 2 has weights 1 and 7 (total weight 8). Join Telegram channel for code discussi

### Movie Festival CSES problem set solution

Movie Festival CSES problem set solution - Problem statement-  Time limit:  1.00 s   Memory limit:  512 MB In a movie festival  n n  movies will be shown. You know the starting and ending time of each movie. What is the maximum number of movies you can watch entirely? Input The first input line has an integer  n n : the number of movies. After this, there are  n n  lines that describe the movies. Each line has two integers  a a  and  b b : the starting and ending times of a movie. Output Print one integer: the maximum number of movies. Constraints 1 ≤ n ≤ 2 ⋅ 10 5 1 ≤ n ≤ 2 ⋅ 10 5 1 ≤ a < b ≤ 10 9 1 ≤ a < b ≤ 10 9 Example Input: 3 3 5 4 9 5 8 Output: 2 Solution - Step -1 take input in a vector as a pair first element is ending time ans second element is starting time Step -2 sort the vector in increasing order because we will watch that movie which is ending first. Step -3 iterate over vector and calculate ans .           follow code below-