## 913 - Joana and the Odd Numbers

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### 913 - Joana and the Odd Numbers

Do i need to precalculate??

how i determine the 1st integer of the line N ????

how i determine the 1st integer of the line N ????

No need to precalculate anything. You can find a general formula to find the last integer in the line N. First list all the numbers -

Line 1 - 1

Line 3 - 7

Line 5 - 17

Line 7 - 31

Line 9 - 49

Line 11 - 71

...

Line N - ?

The formula is not so tough. Try it.

Line 1 - 1

Line 3 - 7

Line 5 - 17

Line 7 - 31

Line 9 - 49

Line 11 - 71

...

Line N - ?

The formula is not so tough. Try it.

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Try the samples

Use 'long long' istead of 'long double'. Dont forget to remove your code. And remember that if you want to post a code then paste your code using 'code' from the editor. Hope these help.

**Input:**Code: Select all

```
99999999
1000000001
```

**Output:**Code: Select all

```
14999999999999991
1500000005999999997
```

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### 913...TLE!!!!

can anyone expain why i am getting TLE for this code

plzzzzzzzzzz help me!!!

thanx

Code: Select all

```
CUT
```

thanx

Last edited by Iffat on Mon Dec 04, 2006 1:17 pm, edited 1 time in total.

Read the previous posts and run your code with those samples. You will find the reason yourself.

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'long long' is not the problem.
If the value of 'n' is big, like 1000000001, then you have to use this loop for (1000000001/2) times. Which is too big. Try to figure out the last odd number in a certain line. You dont have to use any loop. You can find a general formula. Then the result can be found in just O(1) time, which means no loop. Hope you can generate the formula.

Code: Select all

```
while(n!=1)
{
sum=sum+(n*2);
n-=2;
}
```

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functoin pow() returns double, and you are assigning it to a 'long long' variable. So, precision problems can occur easily. Try to get rid of floating point calculations.

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Code: Select all

```
deleted after AC
```

Last edited by laicc86 on Thu Oct 25, 2007 6:59 pm, edited 1 time in total.

The input set contains valid cases. So, no need to check n. And the function should be

Hope these help.

Code: Select all

`long long odd_num(long long num)`

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