There are 4 persons need to cross the bridge.
Unfortunately, they have only one flash light and it has enough light for only 17 minutes.
One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and fourth in 10 minutes to cross the bridge.
Only two members can cross the bridge at a time. How could they cross the bridge within 17 minutes?
Side1: 1 min, 2min, 5min, 10min.
Step1: First send 1 minute and 2 minute guys to another side(takes 2 minutes).
Side1: 5min, 10min
Side2: 1min, 2min
Step2: Send back 1min guy to Side1.
Side1: 1min, 5min, 10min
Step3: send 10 minute and 5 minute guys to side2(takes 10 minutes).
Side2: 10min, 5min, 2min
Step4: Send back 2min guy to Side1.
Side2: 10min, 5min
Step5: Send 2min guy and 1 min guy to Side2(takes 2min).
Side2: 10min, 5min, 1min, 2min