From dc1c5fb9d5f1329dca696f65f8b1dc6fdf20985b Mon Sep 17 00:00:00 2001
From: KongJHong <nail_candy@163.com>
Date: Mon, 29 Oct 2018 16:25:46 +0800
Subject: [PATCH] Create Solution 056[CPP]

---
 solution/056.Merge Intervals/README.md    | 61 +++++++++++++++++++++++
 solution/056.Merge Intervals/Solution.cpp | 36 +++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 solution/056.Merge Intervals/README.md
 create mode 100644 solution/056.Merge Intervals/Solution.cpp

diff --git a/solution/056.Merge Intervals/README.md b/solution/056.Merge Intervals/README.md
new file mode 100644
index 0000000000000..21c21f02f9b3a
--- /dev/null
+++ b/solution/056.Merge Intervals/README.md	
@@ -0,0 +1,61 @@
+给出一个区间的集合，请合并所有重叠的区间。
+```
+示例 1:
+输入: [[1,3],[2,6],[8,10],[15,18]]
+输出: [[1,6],[8,10],[15,18]]
+解释: 区间 [1,3] 和 [2,6] 重叠, 将它们合并为 [1,6].
+
+示例 2:
+输入: [[1,4],[4,5]]
+输出: [[1,5]]
+解释: 区间 [1,4] 和 [4,5] 可被视为重叠区间。
+```
+
+-------------------
+思路：
+
+1. 对容器按start值从小到大排序
+2. 两两顺序比较，用第一个元素的end值和第二个元素的start值比较
+3. 如果后start比前end小，且前end比后end小，则合并！
+4. 不满足3，则直接插入
+
+时间复杂度O(n)
+
+```CPP
+/**
+ * Definition for an interval.
+ * struct Interval {
+ *     int start;
+ *     int end;
+ *     Interval() : start(0), end(0) {}
+ *     Interval(int s, int e) : start(s), end(e) {}
+ * };
+ */
+bool cmp(Interval &val1,Interval &val2){
+    return !(val1.start >= val2.start);
+}
+
+class Solution {
+public:
+    vector<Interval> merge(vector<Interval>& intervals) {
+       
+        int len = intervals.size();
+        if(len <= 1)return intervals;
+        
+        sort(intervals.begin(),intervals.end(),cmp);
+        
+        vector<Interval> ans;
+        ans.push_back(intervals[0]);
+        
+        for(int i = 1;i<len;i++){
+            if(ans.back().end >= intervals[i].start){
+                ans.back().end = max(ans.back().end,intervals[i].end);
+            }
+            else{
+                ans.push_back(intervals[i]);
+            }
+        }
+        return ans;
+    }
+};
+```
\ No newline at end of file
diff --git a/solution/056.Merge Intervals/Solution.cpp b/solution/056.Merge Intervals/Solution.cpp
new file mode 100644
index 0000000000000..4b9fb7a77791a
--- /dev/null
+++ b/solution/056.Merge Intervals/Solution.cpp	
@@ -0,0 +1,36 @@
+/**
+ * Definition for an interval.
+ * struct Interval {
+ *     int start;
+ *     int end;
+ *     Interval() : start(0), end(0) {}
+ *     Interval(int s, int e) : start(s), end(e) {}
+ * };
+ */
+bool cmp(Interval &val1,Interval &val2){
+    return !(val1.start >= val2.start);
+}
+
+class Solution {
+public:
+    vector<Interval> merge(vector<Interval>& intervals) {
+       
+        int len = intervals.size();
+        if(len <= 1)return intervals;
+        
+        sort(intervals.begin(),intervals.end(),cmp);
+        
+        vector<Interval> ans;
+        ans.push_back(intervals[0]);
+        
+        for(int i = 1;i<len;i++){
+            if(ans.back().end >= intervals[i].start){
+                ans.back().end = max(ans.back().end,intervals[i].end);
+            }
+            else{
+                ans.push_back(intervals[i]);
+            }
+        }
+        return ans;
+    }
+};
\ No newline at end of file