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ABHYAS PREP: REASONING PUZZLES · INPUT–OUTPUT

Input–output machine (one rule per step)

Find the rule from Step 1 (which item moved, and to which end), check it on Step 2, then run it forward. Items not yet arranged keep their input order, so you can write any step directly.

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Worked examples

Example 1 · level 1

A machine rearranges a line of words, one word per step, using the same rule every time. In each step, the word that comes last in dictionary order not yet arranged moves to the left end, next to the words already arranged there. If the next word is already in its place, it is skipped without using a step. Input: jasmine falooda henna mango pepper kite Step 1: pepper jasmine falooda henna mango kite Step 2: pepper mango jasmine falooda henna kite What is Step 4?

  1. pepper kite mango jasmine henna falooda
  2. mango pepper kite jasmine henna falooda
  3. pepper mango kite jasmine henna falooda
  4. pepper mango kite jasmine falooda henna
Show solution
  1. Rule: In each step, the word that comes last in dictionary order not yet arranged moves to the left end, next to the words already arranged there.
  2. Step 1: pepper jasmine falooda henna mango kite
  3. Step 2: pepper mango jasmine falooda henna kite
  4. Step 3: pepper mango kite jasmine falooda henna
  5. Step 4: pepper mango kite jasmine henna falooda
  6. What is Step 4? → pepper mango kite jasmine henna falooda.

Answer: pepper mango kite jasmine henna falooda

Example 2 · level 2

A machine rearranges a line of words, one word per step, using the same rule every time. If the next word is already in its place, it is skipped without using a step. Input: lotus ladoo chai temple kite idli Step 1: chai lotus ladoo temple kite idli Step 2: chai idli lotus ladoo temple kite What is Step 4?

  1. idli chai kite ladoo lotus temple
  2. chai idli kite ladoo lotus temple
  3. chai kite idli ladoo lotus temple
  4. chai idli kite lotus ladoo temple
Show solution
  1. Rule: In each step, the word that comes first in dictionary order not yet arranged moves to the left end, next to the words already arranged there.
  2. Step 1: chai lotus ladoo temple kite idli
  3. Step 2: chai idli lotus ladoo temple kite
  4. Step 3: chai idli kite lotus ladoo temple
  5. Step 4: chai idli kite ladoo lotus temple
  6. What is Step 4? → chai idli kite ladoo lotus temple.

Answer: chai idli kite ladoo lotus temple

Example 3 · level 3

A machine rearranges a line of numbers, one number per step, using the same rule every time. If the next number is already in its place, it is skipped without using a step. Input: 57 31 98 64 32 14 39 Step 1: 98 57 31 64 32 14 39 Step 2: 98 64 57 31 32 14 39 In Step 3, which number is first from the right end?

  1. 14
  2. 32
  3. 39
  4. 98
Show solution
  1. Rule: In each step, the largest number not yet arranged moves to the left end, next to the numbers already arranged there.
  2. Step 1: 98 57 31 64 32 14 39
  3. Step 2: 98 64 57 31 32 14 39
  4. Step 3: 98 64 57 39 31 32 14
  5. Step 4: 98 64 57 39 32 31 14
  6. In Step 3, which number is first from the right end? → 14.

Answer: 14

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