feat: add 057

Author: Blankj

README.md

@@ -67,7 +67,7 @@
 |43|[Multiply Strings][043]|Math, String|
 |49|[Group Anagrams][049]|Hash Table, String|
 |50|[Pow(x, n)][050]|Math, Binary Search|
-|56|[Merge Intervals][056]|Math, Binary Search|
+|56|[Merge Intervals][056]|Array, Sort|
 |554|[Brick Wall][554]|Hash Table|
 
 
@@ -80,6 +80,7 @@
 |23|[Merge k Sorted Lists][023]|Linked List, Divide and Conquer, Heap|
 |25|[Reverse Nodes in k-Group][025]|Linked List|
 |44|[Reverse Nodes in k-Group][044]|String, Dynamic Programming, Backtracking, Greedy|
+|57|[Insert Interval][057]|Array, Sort|
 
 
 
@@ -140,3 +141,4 @@
 [023]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/023/README.md
 [025]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/025/README.md
 [044]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/044/README.md
+[057]: https://github.com/Blankj/awesome-java-leetcode/blob/master/note/057/README.md

note/057/README.md

@@ -0,0 +1,71 @@
+# [Insert Interval][title]
+
+## Description
+
+Given a set of *non-overlapping* intervals, insert a new interval into the intervals (merge if necessary).
+
+You may assume that the intervals were initially sorted according to their start times.
+
+**Example 1:**
+Given intervals `[1,3],[6,9]`, insert and merge `[2,5]` in as `[1,5],[6,9]`.
+
+**Example 2:**
+Given `[1,2],[3,5],[6,7],[8,10],[12,16]`, insert and merge `[4,9]` in as `[1,2],[3,10],[12,16]`.
+
+This is because the new interval `[4,9]` overlaps with `[3,5],[6,7],[8,10]`.
+
+**Tags:** Array, Sort
+
+
+## 思路
+
+题意是给你一组有序区间，和一个待插入区间，让你待插入区间插入到前面的区间中，我们分三步走：
+1. 首先把有序区间中小于待插入区间的部分加入到结果中；
+2. 其次是插入待插入区间，如果有交集的话取两者交集的端点值；
+3. 最后把有序区间中大于待插入区间的部分加入到结果中；
+
+```java
+/**
+ * Definition for an interval.
+ * public class Interval {
+ * int start;
+ * int end;
+ * Interval() { start = 0; end = 0; }
+ * Interval(int s, int e) { start = s; end = e; }
+ * }
+ */
+class Solution {
+ public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
+ if (intervals.isEmpty()) return Collections.singletonList(newInterval);
+ List<Interval> ans = new ArrayList<>();
+ int i = 0, len = intervals.size();
+ for (; i < len; ++i) {
+ Interval interval = intervals.get(i);
+ if (interval.end < newInterval.start) ans.add(interval);
+ else break;
+ }
+ for (; i < len; ++i) {
+ Interval interval = intervals.get(i);
+ if (interval.start <= newInterval.end) {
+ newInterval.start = Math.min(newInterval.start, interval.start);
+ newInterval.end = Math.max(newInterval.end, interval.end);
+ } else break;
+ }
+ ans.add(newInterval);
+ for (; i < len; ++i) {
+ ans.add(intervals.get(i));
+ }
+ return ans;
+ }
+}
+```
+
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我GitHub上的LeetCode题解：[awesome-java-leetcode][ajl]
+
+
+
+[title]: https://leetcode.com/problems/insert-interval
+[ajl]: https://github.com/Blankj/awesome-java-leetcode

src/com/blankj/medium/_057/Solution.java

@@ -0,0 +1,46 @@
+package com.blankj.medium._057;
+
+import com.blankj.structure.Interval;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * <pre>
+ * author: Blankj
+ * blog : http://blankj.com
+ * time : 2017/10/24
+ * desc :
+ * </pre>
+ */
+public class Solution {
+ public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
+ if (intervals.isEmpty()) return Collections.singletonList(newInterval);
+ List<Interval> ans = new ArrayList<>();
+ int i = 0, len = intervals.size();
+ for (; i < len; ++i) {
+ Interval interval = intervals.get(i);
+ if (interval.end < newInterval.start) ans.add(interval);
+ else break;
+ }
+ for (; i < len; ++i) {
+ Interval interval = intervals.get(i);
+ if (interval.start <= newInterval.end) {
+ newInterval.start = Math.min(newInterval.start, interval.start);
+ newInterval.end = Math.max(newInterval.end, interval.end);
+ } else break;
+ }
+ ans.add(newInterval);
+ for (; i < len; ++i) {
+ ans.add(intervals.get(i));
+ }
+ return ans;
+ }
+
+ public static void main(String[] args) {
+ Solution solution = new Solution();
+ Interval.print(solution.insert(Interval.createTestData("[1,3],[6,9]"), new Interval(2, 5)));
+ Interval.print(solution.insert(Interval.createTestData("[1,2],[3,5],[6,7],[8,10],[12,16]"), new Interval(4, 9)));
+ }
+}