Puzzle | Human Zombie

This is a problem in which 4 people are their s1, s2, s3, s4 and there is a Bridge.These 4 people came to know that zombie will going to attack them after 17 minutes.Now the situation is like there is a lantern and at a time at most 2 people can cross the bridge but only with lantern and now here are the time that each person takes to cross bridge: 

s1–> 1 minute 
s2–> 2 minutes 
s3–> 8 minutes 
s4–> 10 minutes 

Now we need to find out that whether is it possible that all 4 people will reach the other side of the bridge and cut the rope in 17 minutes. 

Answer: YES 

Explanation:
We need to sort them in ascending order of time i.e 1, 2, 8, 10 then we will send 1 & 2 so total time taken to cross bridge is 2 min and time to come back to start point by s1 is 1 min. 
Now we will take next 2 i.e 10 & 8 minutes people and will send them so total time required would be 10 minutes 
So overall its 1+2+10=13 minutes. 
Now s2 with time of 2 minutes will come back with lantern so total time is 13+2 minutes. 
And then s1 & s2 will go back 15+2 minutes. 

In this way everyone is able to cross bridge and then they will close the bridge. 

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