Simplify struct declarations of C.

Use PascalCase for all structs in C.
SImplify n_queens.c
Format C code for chapter of graph.

codes/c/chapter_divide_and_conquer/binary_search_recur.c

@@ -42,6 +42,6 @@ int main() {
     // 二分查找（双闭区间）
     int index = binarySearch(nums, target, numsSize);
     printf("目标元素 6 的索引 = %d\n", index);
-    
+
     return 0;
 }