While Loop Break

Question

My Python code contains an infinite loop. How can I terminate the infinite loop?

colour = input("Which colour do you prefer? Y-R: ")
while colour not in {"Y", "R"}:
    print("Please, you have to choose only Y - R.")
    colour = input("Which colour do you prefer? Y-R: ")
    while colour in {"Y", "R"}:
      if colour == "Y":
         print("First player: Y")
         print("Second player: R")
      else:
         print("First player: R")
         print("Second player: Y")

Answer 1

Use break :

colour = input("Which colour do you prefer? Y-R: ")
while colour not in ["Y", "R"]:
    print("Please, you have to choose only Y - R.")
    colour = input("Which colour do you prefer? Y-R: ")
    if colour in ["Y", "R"]:
      if colour == "Y":
         print("First player: Y")
         print("Second player: R")
         break
      else:
         print("First player: R")
         print("Second player: Y")
         break

However this is a better solution:

colour = input("Which colour do you prefer? Y-R: ")       
 
while colour not in ["Y", "R"]:
    print("Please, you have to choose only Y - R.")
    colour = input("Which colour do you prefer? Y-R: ")


if colour == "Y":
    print("First player: Y")
    print("Second player: R")
else:
    print("First player: R")
    print("Second player: Y")

Answer 2

You really only need a single loop.

while True:
    colour = input("Which colour do you prefer? Y-R: ")
    
    if colour in {"Y", "R"}:
        first, second = "YR" if colour == "Y" else "RY"
        break

    print("Please, you have to choose only Y - R.")

print(f"First player: {first}")
print(f"Second player: {second}")