Interview Questions of Alibaba Technology Department-collection of classic intellectual issues

 

Technical Department interview questions-collection of classic intellectual issues
The first part of the question begins:
1. There are two unevenly distributed fragrances. The burning time is one hour. How can you determine a period of 15 minutes?

2. A manager has three daughters. The three daughters are 13 years old, and the three daughters are equal to the manager's age. One subordinate has an known manager's age, however, I still cannot determine the age of the three daughters of the manager. The manager said that only one daughter had a black hair, and the subordinate knew the age of the three daughters of the manager. What is the age of the three daughters? Why?

3. Three people went to the hotel and stayed in three rooms. Each room was $10 yuan, so they paid the boss $30 in total. The next day, the boss thinks that only $25 is required for the three rooms, so he asks the younger brother to return $5 to the three guests. Who knows the younger brother is greedy and only returns $1 to each user, who secretly takes $2, in this way, nine yuan is spent for each of the three guests, and $27 is spent for each of the three guests. In addition, the younger brother swallowed $2 for a total of $29. But when the three of them paid a total of $30, what about $1?

4. Two blind people bought two black so and two white so. The eight so have the same cloth quality and size, and each so has a trademark paper attached. The two blind people accidentally mixed up the eight-to-eight so. How can they retrieve black and white so pairs?

5. One train leaves Los Angeles at a rate of 15 kilometers per hour and goes straight to New York. The other train departs from New York to Los Angeles at a rate of 20 kilometers per hour. If a bird starts at a speed of 30 kilometers per hour and two trains start at the same time, it departs from Los Angeles and returns when it encounters another car. In turn, the two trains fly back and forth, it wasn't until two trains met. How long did the bird fly?

6. You have two cans, 50 red balls and 50 blue balls. You can select a random jar and place a ball in the jar. How can you give the biggest chance to select a red ball? In your plan, what is the exact chance of getting a red ball?

7. You have four cans containing pills. Each pill has a certain weight. The contaminated pills are not contaminated. + 1. how can I determine which jar of medicine is contaminated once?

8. You have a bucket of jelly, including yellow, green, and Red. Close your eyes and capture the jelly in the same color. You can determine if you have two joos of the same color after capturing them?

9. For a batch numbered 1 ~ 100, all turn on (on) the light to perform the following operations: All the multiples of 1 turn back one switch; 2 multiple turn back one switch; turn another switch in the opposite direction in multiples of 3 ...... Q: It is the number of the light that is turned off.

10. Imagine that you are in front of the mirror. Why can't images in the mirror be upside down, but not upside down?

11. A group of people wear a hat on their heads. There are only black and white hats, and at least one black hat. Everyone can see the colors of others' hats, but not their own. The host will show you what hats others wear on their heads and turn off the lights. If someone thinks they are wearing black hats, they will slap themselves in the face. Turn off the light for the first time and there is no sound. Then we turned on the light and watched it again. When the light was turned off, it was still silent. It was not until the third time that the light was turned off that there was a slap in the face. How many people are wearing black hats?

12. The radius of the two rings is 1 and 2 respectively. The circle is centered around the circumference of the circle for one week. How many weeks have the circle itself been rotated? What if the circle itself turns around for weeks outside the circle?

13. If someone buys 10 bottles of beer for every 3 empty beer bottles, how many bottles of beer can he drink at most?
Answer:
1. xianga ignment, xiangb ignment. It took 30 minutes to finish burning xiangb. Then the other end of xianga is ignited. From this time to the end of a's burning time is 15 minutes.

2. Three women should be 2, 2, and 9. Because there is only one

The child has black hair, that is, when she grows up, and the other two are younger than 3 years old, her hair is pale. The manager's age should be at least 25.

3. Typical theft and exchange concepts. In fact, three people only paid 27 yuan, the boss got 25 yuan, and the younger brother took 2 yuan.

4. Split each pair of sock into one.

5. The distance from Los Angeles to New York is a kilometer long. It took a/(15 + 20) hours for the two trains to arrive, that is, the time when the birds flew. Therefore, the distance between the bird flight is the length of the railway from Los Angeles to New York at a speed × time = 30 × A/35 = 6/7.

6. 1/2 probability. First select the ball in the selection pot. In this way, the jar has no effect on the color of the ball.

7. 1 can take 1 pill, 2 can take 2 pills, 3 can take 3 pills, 4 can take 4 pills, weigh the 10 pills, A few more than the normal weight is a problem with the number of cans of medicine.

8 and 4. Quantity> color type. The color must be repeated.

9. There are 10 lights that are off, respectively, 1, 4, 9, 16, 25, 36, 49, 64, 81, and 100. Because each prime number can be divisible by one and itself, the lamp of the prime number is on. If a sum can be divisible by N numbers, N must be an even number. For a combination of not a certain number of square, it will be switched n times, that is, even number of times, the lamp is kept on; for the number of times listed above, it is switched only N-1 times, so the light is off.

10. The symmetrical axis of the image is the center axis of the person.

11. Three people wear black hats. Suppose n people wear black. When n = 1, when black people see that others are white, they must be black. So the first time you turn off the light, there should be a sound. N> 1 can be determined. For everyone in black, he could see the N-1 with a black hat and assume that he was white. But after waiting for N-1 times no one beat themselves, every wearing black can know that they are also black. So n people turn off the lights for the nth time.

12. The circle turns into two circles regardless of the inside and outside.

13. After drinking 10 bottles, use 9 empty bottles for 3 bottles of beer (4 empty bottles after drinking). After drinking these three bottles, you can change to 1 bottle of beer (2 empty bottles after drinking)
At this time, he had two empty bottles. If he could borrow an empty bottle from his boss, he would have enough space for three empty bottles to replace with a beer, after drinking the bottle, you can return the empty bottle to the boss.
So he can drink at most 10 + 3 + 1 + 1 = 15 bottles