Merge intervals

Author: ratulb

codes/merge_intervals.mojo

@@ -0,0 +1,54 @@
+### Merge Itervals
+### Merge overlapping intervals
+
+
+@parameter
+fn compare_fn(interval1: (Int, Int), interval2: (Int, Int)) -> Bool:
+    return interval1[0] < interval2[0]
+
+
+fn merge_intervals(mut intervals: List[(Int, Int)]) -> List[(Int, Int)]:
+    if len(intervals) == 0:
+        return List[(Int, Int)]()
+
+    sort[compare_fn](intervals)
+
+    result = List[(Int, Int)]()
+    result.append(intervals[0])
+    for curr_interval in intervals[1:]:
+        start, end = curr_interval[]
+        last_interval = result[-1]
+        last_start, last_end = last_interval
+        if start <= last_end:
+            result[len(result) - 1] = (last_start, max(last_end, end))
+        else:
+            result.append(curr_interval[])
+
+    return result
+
+
+from testing import assert_true
+
+
+fn main() raises:
+    intervals = List[(Int, Int)]((1, 3), (2, 6), (8, 10), (15, 18))
+    expected = List[(Int, Int)]((1, 6), (8, 10), (15, 18))
+    result = merge_intervals(intervals)
+    i = 0
+    for each in result:
+        assert_true(
+            each[][0] == expected[i][0] and each[][1] == expected[i][1],
+            "Assertion failed",
+        )
+        i += 1
+
+    intervals = List[(Int, Int)]((1, 4), (4, 5))
+    expected = List[(Int, Int)]((1, 5))
+    result = merge_intervals(intervals)
+    i = 0
+    for each in result:
+        assert_true(
+            each[][0] == expected[i][0] and each[][1] == expected[i][1],
+            "Assertion failed",
+        )
+        i += 1

docs/index.md

@@ -67,4 +67,6 @@
 
 🟢 [Find All Anagrams in a String](all_anagrams.md) ➔ Return all start indices of anagrams of string p in string s.
 
-🟢 [Find First/Last](find_first_last.md) ➔ Find first and last index of a target value in a sorted array
+🟢 [Find First/Last](find_first_last.md) ➔ Find first and last index of a target value in a sorted array
+
+🟢 [Merge Itervals](merge_intervals.md) ➔ Merge overlapping intervals

docs/merge_intervals.md

@@ -0,0 +1,61 @@
+### Merge Itervals
+### Merge overlapping intervals
+
+```python
+
+
+@parameter
+fn compare_fn(interval1: (Int, Int), interval2: (Int, Int)) -> Bool:
+    return interval1[0] < interval2[0]
+
+
+fn merge_intervals(mut intervals: List[(Int, Int)]) -> List[(Int, Int)]:
+    if len(intervals) == 0:
+        return List[(Int, Int)]()
+
+    sort[compare_fn](intervals)
+
+    result = List[(Int, Int)]()
+    result.append(intervals[0])
+    for curr_interval in intervals[1:]:
+        start, end = curr_interval[]
+        last_interval = result[-1]
+        last_start, last_end = last_interval
+        if start <= last_end:
+            result[len(result) - 1] = (last_start, max(last_end, end))
+        else:
+            result.append(curr_interval[])
+
+    return result
+
+
+from testing import assert_true
+
+
+fn main() raises:
+    intervals = List[(Int, Int)]((1, 3), (2, 6), (8, 10), (15, 18))
+    expected = List[(Int, Int)]((1, 6), (8, 10), (15, 18))
+    result = merge_intervals(intervals)
+    i = 0
+    for each in result:
+        assert_true(
+            each[][0] == expected[i][0] and each[][1] == expected[i][1],
+            "Assertion failed",
+        )
+        i += 1
+
+    intervals = List[(Int, Int)]((1, 4), (4, 5))
+    expected = List[(Int, Int)]((1, 5))
+    result = merge_intervals(intervals)
+    i = 0
+    for each in result:
+        assert_true(
+            each[][0] == expected[i][0] and each[][1] == expected[i][1],
+            "Assertion failed",
+        )
+        i += 1
+
+```
+
+
+[Source](https://github.com/ratulb/mojo_programming/blob/main/codes/merge_intervals.mojo)