init impl

Author: freemanzhang

src/interval/NonOverlappingIntervals.java

@@ -0,0 +1,60 @@
+package interval;
+
+import java.util.Arrays;
+
+import utility.Interval;
+
+/*
+Given a collection of intervals, find the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.
+
+Note:
+You may assume the interval's end point is always bigger than its start point.
+Intervals like [1,2] and [2,3] have borders "touching" but they don't overlap each other.
+Example 1:
+Input: [ [1,2], [2,3], [3,4], [1,3] ]
+
+Output: 1
+
+Explanation: [1,3] can be removed and the rest of intervals are non-overlapping.
+Example 2:
+Input: [ [1,2], [1,2], [1,2] ]
+
+Output: 2
+
+Explanation: You need to remove two [1,2] to make the rest of intervals non-overlapping.
+Example 3:
+Input: [ [1,2], [2,3] ]
+
+Output: 0
+
+Explanation: You don't need to remove any of the intervals since they're already non-overlapping.
+Show Tags
+Show Similar Problems
+
+ * */
+
+public class NonOverlappingIntervals
+{
+    public int eraseOverlapIntervals( Interval[] intervals )
+    {
+    	if ( intervals.length == 0 )
+    	{
+    		return 0;
+    	}
+    	
+    	Arrays.sort( intervals, ( o1, o2 ) -> o1.end - o2.end );
+    	int result = 0;
+    	int end = intervals[0].end;
+    	
+    	for ( int i = 1; i < intervals.length; i++ )
+    	{
+    		if ( intervals[i].start >= end )
+    		{
+    			end = intervals[i].end;
+    			result++;
+    		}
+    	}
+    	
+    	return intervals.length - result;
+    }
+}