triangle challenge

Hi,

I am working on below challenge

http://codingbat.com/prob/p194781

Recursion-1 > triangle
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We have triangle made of blocks. The topmost row has 1 block, the next row down has 2 blocks, the next row has 3 blocks, and so on. Compute recursively (no loops or multiplication) the total number of blocks in such a triangle with the given number of rows.

triangle(0) → 0
triangle(1) → 1
triangle(2) → 3

i have not understood above description.
what is row and what is block and how they are related to triange and what we have to return
Can you please advise

JavaJava EEProgrammingGame ProgrammingSmartphone Programming

Last Comment

gudii9

8/22/2022 - Mon

ASKER CERTIFIED SOLUTION

rrz

9/9/2016

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gudii9

9/9/2016

ASKER

i understood now with above image.

public int triangle(int rows) {
  if(rows==1){
    return 1;
  }
  return rows+triangle(rows-1);
}

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above fails one test case

xpected      Run
triangle(0) → 0      Exception:java.lang.StackOverflowError (line number:2)      X
triangle(1) → 1      1      OK
triangle(2) → 3      3      OK
triangle(3) → 6      6      OK
triangle(4) → 10      10      OK
triangle(5) → 15      15      OK
triangle(6) → 21      21      OK
triangle(7) → 28      28      OK
other tests

how to decide base case begin with 0 or with 1. it is failing 0 case now

rrz

9/9/2016

how to decide base case begin with 0

Just do the same with base case with 0 instead of 1.

gudii9

9/11/2016

ASKER

with one failing one.

with 0 base case all passing

public int triangle(int rows) {
  if(rows==0){
    return 0;
  }
  return rows+triangle(rows-1);
}

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