1 files changed, 33 insertions, 0 deletions
diff --git a/others/other/biendoiso.py b/others/other/biendoiso.py
new file mode 100755
index 0000000..4b5e09d
--- /dev/null
+++ b/others/other/biendoiso.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+from math import gcd
+
+
+def xgcd(a, b):
+    """Return a tuple (u, v), such that u*a + v*b == gcd(a, b).
+
+    https://en.wikibooks.org/wiki/Algorithm_Implementation/Mathematics/Extended_Euclidean_algorithm#Iterative_algorithm
+    """
+    u0, u1, v0, v1 = 1, 0, 0, 1
+    while b:
+        q, a, b = a // b, b, a % b
+        u0, v0, u1, v1 = u1, v1, u0 - q*u1, v0 - q*v1
+    return u0, v0
+
+
+def biendoiso(a, b, c):
+    g = gcd(a, b)
+    if c % g:
+        return -1
+    elif not c % a:
+        return c // a
+    elif not c % b:
+        return c // b
+    if a > b: a, b = b, a
+    u, v = map(lambda n: n * c // g, xgcd(a, b))
+    m = u * g // b
+    return u + v + m*(a-b)
+
+
+with open('biendoiso.inp') as fi, open('biendoiso.out', 'w') as fo:
+    x, y, a, b = map(int, fi.read().split())
+    fo.write('{}\n'.format(biendoiso(a, b, y - x)))