solve "228. Summary Ranges"

.plan

@@ -1,3 +1,7 @@
+Sep 17, 2024
+
+* solve "228. Summary Ranges"
+
 Sep 16, 2024
 
 * re-solve question 28 using Knuth–Morris–Pratt

src/summary_ranges.py

@@ -0,0 +1,23 @@
+class Solution:
+    def summaryRanges(self, nums: list[int]) -> list[str]:
+        if not nums:
+            return []
+
+        result: list[str] = []
+        left = right = nums[0]
+
+        def append() -> None:
+            if left == right:
+                result.append(f"{left}")
+            else:
+                result.append(f"{left}->{right}")
+
+        for i in range(1, len(nums)):
+            if nums[i] == right + 1:
+                right = nums[i]
+            else:
+                append()
+                left = right = nums[i]
+
+        append()
+        return result

tests/test_summary_ranges.py

@@ -0,0 +1,14 @@
+import pytest
+
+from src.summary_ranges import Solution
+
+
+@pytest.mark.parametrize(
+    "expected,nums",
+    (
+        (["0->2", "4->5", "7"], [0, 1, 2, 4, 5, 7]),
+        (["0", "2->4", "6", "8->9"], [0, 2, 3, 4, 6, 8, 9]),
+    ),
+)
+def test_solution(expected, nums):
+    assert expected == Solution().summaryRanges(nums)