Qualcomm Interview Questions: Bridge and torch problem : Four people come to a river in th

Asked inQualcomm,Software Engineer

Bridge and torch problem : Four people come to a river in the night. There is a narrow bridge, but it can only hold two people at a time. They have one torch and, because it's night, the torch has to be used when crossing the bridge. Person A can cross the bridge in 1 minute, B in 2 minutes, C in 7 minutes, and D in 10 minutes. When two people cross the bridge together, they must move at the slower person's pace. What is the least time taken for them to get across the bridge?

Anonymous

VINAYANADH.V.R

Answer is 17. A and B cross the bridge. A comes back. Time taken 3 minutes. Now B is on the other side.C and D cross the bridge. B comes back. Time taken 10 + 2 = 12 minutes. Now C and D are on the ot...read more

Mayur Jadhav

2 + 1 + 10 + 2 + 2 = 17 minutes Thus, the least time required for all four people to cross is 17 minutes.

Anonymous

Answering 17 minutes a and b first cross the bridge in 2 minutes and a 1 minute again trouser balance 14 minutes in be and c slower they bridge cross in 10 minutes balance 4 minutes b again cross the ...read more

JEYA BELLA D

Sahil Thakur

student at

Rayat & Bahra Institute of Engineering & Bio-Technology, Kharar

answer is 17 because here is 4 people a and b cross the bridge together with the speed of <2> mint or unke pass torch bhi hai and then A baapis jaayega torch dene C or D ke pass speed <1> and then C o...read more

Kamrul Hoda

7mints

priti gupta

10 minutes

Anonymous

10d

8 minutes

Anonymous

13d

25 minutes

Anonymous

14d

Anonymous

20d

17 minutes

Pranav Gangurde

21d

It will take 21 mins 10+1=10 (max time taken to cross bridge) 1=return time 7+1=7 (max time taken to cross bridge 2nd time) 1=return time 2 2+1=2 (max time taken to cross bridge 3rd time) 10+1+7+1+2=2...read more

sandeep ramini

25d

Ans is 17 mins Initial Crossing Person A and Person B cross the bridge together, taking 2 minutes (since B is slower). The torch is now on the other side.Returning the Torch Person A returns with the ...read more

Vishal Soni

29d

ex -

Tech Panda

A and B cross (2 minutes): The fastest two go together. A returns (1 minute): The fastest person comes back with the torch. C and D cross (10 minutes): The slowest two go together. B returns (2 minute...read more

SUGANYA.G

1mo

17 mins

Prachi Dhere

1mo

It will take 20 min time to cross the bridge.

dhanalakshmi jm

1mo

12 mins

Anonymous

1mo

17minute

Sejalkumari Rajeshbhai Chaudhari

1mo

Anonymous

1mo

17 minutes

Anonymous

1mo

Total 5 minutes lagega

Anonymous

1mo

पहिले A, B और c को ७ मिनट में पुल पार करेगा फिर वापिस आयेगा १ मिनट में फिर D को १० मिनट में पार करेगा । सभी लोगो को पहुंचाने में १८ मिनट लगेगा ।

Anonymous

2mo

12 minutes because the a and b corss the bridge at same time then a and b corss the bridge in both corss the bridge in 2 minutes and c and d both cross bridge in 10 minutes so the total time is 10+2 =...read more

rythm31

29d

ex -

Tech Panda

who will go back to give them torch back?

Anonymous

2mo

Total time taken will be 17 minutes

sarthak dhage

2mo

17= 2+1+10+2+2

Kiran Nayak

2mo

works at

Paytm

Total time taken is :2+1+10+2+2= 17

Anonymous

2mo

All cross Brigade night =17 Minutes

VINOTH BABU

2mo

17 min

RAHUL TIWARI

2mo

1. A and B cross the bridge together (2 minutes). Torch is with them. 2. A returns with the torch (1 minute). Total time: 3 minutes. 3. C and D cross the bridge together (10 minutes). Torch is with th...read more

Mihir Vikram Singh Chauhan

3mo

10 min A uses torch and crosses with B That is 2 minutes. Then A returns and crosses with C that is 7 minutes. => 2+1+7=10

Satya Narayana Reddy

3mo

17 minutes

Parvez Hakim

3mo

Step 1: A and B cross the bridge. A comes back. Time taken 3 minutes. Now B is on the other side. Step 2: C and D cross the bridge. B comes back. Time taken 8 + 2 = 10 minutes. Now C and D are on the ...read more

Anonymous

4mo

Sir, this question is wrong as long as it does not measure the length of the pool or the speed of the bucket.

Anonymous

4mo

Anonymous

4mo

Adithya CP

4mo

Total time taken will be 21 minutes

Anonymous

4mo

kiran babu

4mo

17 minutes

Sunita Tiwary

4mo

They will cross bridge in total 10 minutes. D will start with torch every time in his hand. First A will join him and reach other side of the bridge , followed by B who will reach the other side in 2 ...read more

Anonymous

4mo

A @ D will take to 10 minutes to cross the bridge so all of them will take 21 minutes to cross the bridge

Devika K.S

4mo

ex -

State Bank of India

The bridge and torch problem (also known as The Midnight Train[1] and Dangerous crossing[2]) is a logic puzzle that deals with four people, a bridge and a torch. It is in the category of river crossin...read more

Hillan Shaba

4mo

currently not working

A&D will take 10 minutes to cross the bridge. So all of them will take 21 minutes to cross the bridge.

Praveen Singh

5mo

7 minutes with each for crossing the bridge.

Akshay Lilhare

5mo

Step 1: 2 minutes (A and B cross) Step 2: 1 minute (A returns) Step 3: 10 minutes (C and D cross) Step 4: 2 minutes (B returns) Step 5: 2 minutes (A and B cross again) Total Time = 2 + 1 + 10 + 2 + 2 ...read more

Anonymous

5mo

17 minutes

Hillan Shaba

5mo

currently not working

17 minutes