Update 0056.合并区间.md

0056.合并区间新增C语言实现

problems/0056.合并区间.md

@@ -336,7 +336,49 @@ impl Solution {
     }
 }
 ```
+### C
+
+```c
+#define max(a, b) ((a) > (b) ? (a) : (b))
+
+// 根据左边界进行排序
+int cmp(const void * var1, const void * var2){
+    int *v1 = *(int **) var1;
+    int *v2 = *(int **) var2;
+    return v1[0] - v2[0];
+}
+
+int** merge(int** intervals, int intervalsSize, int* intervalsColSize, int* returnSize, int** returnColumnSizes) {
+    int ** result = malloc(sizeof (int *) * intervalsSize);
+    * returnColumnSizes = malloc(sizeof (int ) * intervalsSize);
+    for(int i = 0; i < intervalsSize; i++){
+        result[i] = malloc(sizeof (int ) * 2);
+    }
+    qsort(intervals, intervalsSize, sizeof (int *), cmp);
+    int count = 0;
+    for(int i = 0; i < intervalsSize; i++){
+        // 记录区间的左右边界
+        int L = intervals[i][0], R = intervals[i][1];
+        // 如果count为0或者前一区间的右区间小于此时的左边，加入结果中
+        if (count == 0 || result[count - 1][1] < L) {
+            returnColumnSizes[0][count] = 2;
+            result[count][0] = L;
+            result[count][1] = R;
+            count++;
+        } 
+        else{ // 更新右边界的值
+            result[count - 1][1] = max(R, result[count - 1][1]);
+        }
+    }
+    *returnSize = count;
+    return result;
+}
+```
+
+
+
 ### C#
+
 ```csharp
 public class Solution
 {
@@ -367,4 +409,3 @@ public class Solution
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
-