create dev channel

zeta/py/32526.py

@@ -0,0 +1,31 @@
+class ConstructString:
+    def __init__(self, n, k):
+        self.n = n
+        self.k = k
+
+    def solve(self) -> tuple[str]:
+        if self.k == 0:
+            if self.n <= 2:
+                return ("No",)
+            else:
+                return "Yes", "abc" * self.n // 3 + "abc"[: self.n % 3]
+        elif self.k == self.n - 1:
+            return "Yes", "a" * self.n
+
+        s = [-1] * self.n
+        for i in range(self.k):
+            s[i] = 0
+            s[self.n - i - 1] = 0
+        
+        if self.n - self.k - 1 >= self.k and s[self.n - self.k - 1] == -1:
+            s[self.n - self.k - 1] = 1
+        
+        for i in range(self.n):
+            if s[i] == -1:
+                s[i] = 2
+
+        return "Yes", s 
+if __name__ == "__main__":
+    n, k = map(int, input().split())
+    solver = ConstructString(n, k)
+    print(*solver.solve(), sep="\n")