程序調試遇到錯誤：Program terminated with signal SIGSEGV, Segmentation fault.SIGSEGV：
在POSIX兼容的平台上，SIGSEGV是當一個進程執行了一個無效的內存引用，或發生段錯誤時發送給它的信號。SIGSEGV的符號常量在頭文件signal.h中定義。
官方說法： SIGSEGV — Segment Fault. The possible cases of your encountering this error are:
1.buffer overflow — usually caused by a pointer reference out of range.
2.stack overflow — please keep in mind that the default stack size is 8192K.
3.illegal file access — file operations are forbidden on our judge system.
