Added task 435.

Author: javadev

src/main/java/g0401_0500/s0435_non_overlapping_intervals/Solution.java

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+package g0401_0500.s0435_non_overlapping_intervals;
+
+// #Medium #Array #Dynamic_Programming #Sorting #Greedy
+
+import java.util.Arrays;
+
+public class Solution {
+    /**
+     * This is sorting my starting time, the key here is that we'll want to update end time when an
+     * erasure is needed: we use the smaller end time instead of the bigger one which is more likely
+     * to overlap with others.
+     */
+    public int eraseOverlapIntervals(int[][] intervals) {
+        Arrays.sort(intervals, (a, b) -> a[0] != b[0] ? a[0] - b[0] : a[1] - b[1]);
+        int erasures = 0;
+        int end = intervals[0][1];
+        for (int i = 1; i < intervals.length; i++) {
+            if (intervals[i][0] < end) {
+                erasures++;
+                end = Math.min(end, intervals[i][1]);
+            } else {
+                end = intervals[i][1];
+            }
+        }
+        return erasures;
+    }
+}

src/main/java/g0401_0500/s0435_non_overlapping_intervals/readme.md

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+435\. Non-overlapping Intervals
+
+Medium
+
+Given an array of intervals `intervals` where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code>, return _the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping_.
+
+**Example 1:**
+
+**Input:** intervals = [[1,2],[2,3],[3,4],[1,3]]
+
+**Output:** 1
+
+**Explanation:** [1,3] can be removed and the rest of the intervals are non-overlapping. 
+
+**Example 2:**
+
+**Input:** intervals = [[1,2],[1,2],[1,2]]
+
+**Output:** 2
+
+**Explanation:** You need to remove two [1,2] to make the rest of the intervals non-overlapping. 
+
+**Example 3:**
+
+**Input:** intervals = [[1,2],[2,3]]
+
+**Output:** 0
+
+**Explanation:** You don't need to remove any of the intervals since they're already non-overlapping. 
+
+**Constraints:**
+
+*   <code>1 <= intervals.length <= 10<sup>5</sup></code>
+*   `intervals[i].length == 2`
+*   <code>-5 * 10<sup>4</sup> <= start<sub>i</sub> < end<sub>i</sub> <= 5 * 10<sup>4</sup></code>

src/test/java/g0401_0500/s0435_non_overlapping_intervals/SolutionTest.java

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+package g0401_0500.s0435_non_overlapping_intervals;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class SolutionTest {
+    @Test
+    void eraseOverlapIntervals() {
+        assertThat(
+                new Solution().eraseOverlapIntervals(new int[][] {{1, 2}, {2, 3}, {3, 4}, {1, 3}}),
+                equalTo(1));
+    }
+
+    @Test
+    void eraseOverlapIntervals2() {
+        assertThat(
+                new Solution().eraseOverlapIntervals(new int[][] {{1, 2}, {1, 2}, {1, 2}}),
+                equalTo(2));
+    }
+
+    @Test
+    void eraseOverlapIntervals3() {
+        assertThat(new Solution().eraseOverlapIntervals(new int[][] {{1, 2}, {2, 3}}), equalTo(0));
+    }
+}