CODEWITHSUNDEEP
pythonpython-3.xwhile-loop
SunnyBoiz
SunnyBoiz

Reputation: 594

While Loop not functioning properly

I am testing a simple linear diophantine equations code. Here is the code:

a = 3
b = 4
n = 67

i = 0
while True:
    if i * a <= n:
        if (n - (i * a)) % b == 0:
                yy = int((n - (i * a)) / b)
                print("{0} x {1} + {2} x {3} = {4}".format(a, i, b, yy, n))
        i = i + 1
    else:
        print("No possible solution!")
        break

When the code is run, it is able to find the possible x and y in this equation (which is fine). But, what I can't figure out is why is the print "No Possible solution!" is getting printed together with the answer. The else block is suppose to appear only if a solution is not possible e.g a = 3, b = 4 and n = 2.

Any advice will be appreciated.

Upvotes: 0

Views: 55

Answers (2)

Joy
Joy

Reputation: 424

Use flag to identify solution is available or not. 

a = 3
b = 4
n = 67

i = 0
isSolutionAvailable=False
while True:
    if i * a <= n:
        if (n - (i * a)) % b == 0:
                yy = int((n - (i * a)) / b)
                print("{0} x {1} + {2} x {3} = {4}".format(a, i, b, yy, n))
                isSolutionAvailable=True
        i = i + 1
    else:
        break
if(not(isSolutionAvailable)):
    print("No possible solution!")

Upvotes: 0

Emrah Diril
Emrah Diril

Reputation: 1765

print("No possible solution!") is inside the else case so it will execute regardless of whether any solutions were found or not.

Here is one way to fix it where a boolean variable keeps track of whether a solution was found or not and prints the message based on the state of that variable:

a = 3
b = 4
n = 2

i = 0
solution_found = False
while True:
    if i * a <= n:
        if (n - (i * a)) % b == 0:
            yy = int((n - (i * a)) / b)
            print("{0} x {1} + {2} x {3} = {4}".format(a, i, b, yy, n))
            solution_found = True
        i = i + 1
    else:
        break

if not solution_found:
    print("No possible solution!")

Upvotes: 1

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