(1) How many chopsticks do you need to take to ensure all three colors?

(2) How many chopsticks should I take to ensure that there are two pairs of chopsticks with different colors?

(3) How many chopsticks should I take to ensure that there are two pairs of chopsticks with the same color?

Test site: pigeon coop principle. Analysis:

(1) The worst case scenario is that chopsticks of two colors are taken, but chopsticks of the third color are not taken. At this time, only one more chopstick can fill the three colors, so at least 20+ 1=2 1 chopstick should be taken;

(2) In the worst case, all the chopsticks of one color are taken away, and the chopsticks of the other two colors are 1 root. At this time, as long as one more chopstick is taken, at least 10+2+ 1 = 13 chopsticks should be taken;

(3) In the worst case, take three chopsticks of each color. At this time, as long as you take one chopstick, you can guarantee two pairs of chopsticks with the same color. So I took at least 3×3+ 1= 10 chopsticks. Solution: (1) 20+ 1 = 265438.

(2)10+2+1=13 (root);

(3)3×3+ 1= 10 (root);

Answer: Take at least 2/kloc-0 chopsticks to ensure all three colors, at least 13 chopsticks to ensure two pairs of chopsticks with different colors, and at least 10 chopsticks to ensure two pairs of chopsticks with the same color.