如果你用 fread() 快读

本体最后一个测试点输入奇特，没有换行符之类的截至读入最后一个数字。平时没问题的快读会 $TLE$。

不妨做出如下改动。

TLE

namespace IO {
	const int IN_LEN = 1 << 21;
	char buf[IN_LEN], *front = buf, *back = buf;
	inline char FastGetchar() {
		if (front >= back) {
			front = buf;
			back = buf + fread(buf, 1, IN_LEN, stdin);
		}
		return *(front++);
	}
	inline int read() {
		int ret = 0;
		char ch = FastGetchar();
		bool flag = false;
		while (ch < '0' || ch > '9') {
			if (ch == '-') {
				flag = true;
			}
			ch = FastGetchar();
		}
		while (ch >= '0' && ch <= '9') {
			ret = ret * 10 + ch - '0';
			ch = FastGetchar();
		}
		return flag ? -ret : ret;
	}
}

AC

namespace IO {
	const int IN_LEN = 1 << 21;
	char buf[IN_LEN], *front = buf, *back = buf;
	bool IO_END=false;
	inline char FastGetchar() {
		if (front >= back) {
			front = buf;
			back = buf + fread(buf, 1, IN_LEN, stdin);
			if(front==back){
			    IO_END=true;
			    return '0';
			}
		}
		return *(front++);
	}
	inline int read() {
		int ret = 0;
		char ch = FastGetchar();
		/*if(IO_END){
		    return ret;
		}*/
		bool flag = false;
		while (ch < '0' || ch > '9') {
			if (ch == '-') {
				flag = true;
			}
			ch = FastGetchar();
			/*if(IO_END){
			    return ret;
			}*/
		}
		while (ch >= '0' && ch <= '9') {
			ret = (unsigned int)ret * 10 + ch - '0';
			ch = FastGetchar();
			if(IO_END){
			    return ret;
			}
		}
		return flag ? -ret : ret;
	}
}