POUR1 - Pouring water

Given two vessels, one of which can accommodate a litres of water and the other - b litres of water, determine the number of steps required to obtain exactly c litres of water in one of the vessels.

At the beginning both vessels are empty. The following operations are counted as 'steps':

  • emptying a vessel,
  • filling a vessel,
  • pouring water from one vessel to the other, without spilling, until one of the vessels is either full or empty.


An integer t, 1<=t<=100, denoting the number of testcases, followed by t sets of input data, each consisting of three positive integers a, b, c, not larger than 40000, given in separate lines.


For each set of input data, output the minimum number of steps required to obtain c litres, or -1 if this is impossible.


Sample input:
Sample output:

hide comments
shiva890: 2022-01-07 05:36:59

I got tle happy

amolmawale813: 2021-10-24 20:37:07

How could we get it's answers??

haiderbaig: 2020-09-06 12:23:37

AC in BFS and unordered_maps to mark visited nodes/states
(Strangely, I was getting TLE when I used large arrays to keep track of visited nodes)

pb_81: 2020-06-10 17:55:01

can anyone please give some corner test cases. As it is difficult to debug without it. I also tested so many cases but did not find the error!

apoorva222g: 2020-03-29 09:26:37

You must simulate by doing "pouring action" only in one jug and "discharging action" only in the opposite jug.

(1)pour in a, discharge in b: if a is empty pour a full, if b is full the discharge and make b empty. Otherwise, transfer water from a to b. Each of those three condition is a step & can happen only once at a time.

(2)pour in b, discharge in a: if b is empty pour it full, if a is full make it empty. Otherwise, transfer water from b to a.

count total steps for (1) and (2), the minimum is the answer.

importme: 2020-03-11 14:41:16

Some optimisations necessary for while using BFS, otherwise TLE. Good question!

parsabn: 2019-10-22 15:44:09

good question .
i solved it using Binary Search

Last edit: 2019-10-22 15:44:39
eagleshadow: 2019-05-25 12:59:49

Nice Question!

abhinav_jain02: 2018-12-21 13:00:35

Good question to ponder. Finally AC using concept of Diophantine equation

masterchef2209: 2018-11-15 12:07:04

ad hoc
if anyone wants to dig deep in this question
see this MIT lecture-https://www.youtube.com/watch?v=NuY7szYSXSw
just keep in mind that we have to take min of algo on (a,b) and (b,a)

Added by:adrian
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS PERL6 VB.NET
Resource:An ancient problem, formulated in these words by Mr Tadeusz Ratajczak