3184 - 求1-n以内所有数和
Time Limit : 1 秒
Memory Limit : 128 MB
<span style="font-family:宋体;font-size:12pt;">【题目描述】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;"><span> </span><span> </span></span><span style="font-family:宋体;font-size:12pt;">给定一个正整数</span><span style="font-size:12pt;">N</span><span style="font-family:宋体;font-size:12pt;">，输出大于等于</span><span style="font-size:12pt;">1</span><span style="font-family:宋体;font-size:12pt;">且小于等于</span><span style="font-size:12pt;">N</span><span style="font-family:宋体;font-size:12pt;">的所有数的和</span><span style="font-size:12pt;"></span>
<span style="font-family:宋体;font-size:12pt;">【输入格式】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;"><span> </span><span> </span></span><span style="font-family:宋体;font-size:12pt;">一个正整数，即</span><span style="font-size:12pt;">N</span>
<span style="font-family:宋体;font-size:12pt;">【输出格式】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;"><span> </span><span> </span></span><span style="font-family:宋体;font-size:12pt;">仅包含一行，即答案</span><span style="font-size:12pt;"></span>
<span style="font-family:宋体;font-size:12pt;">【样例输入】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;"><span> </span><span> </span>10</span>
<span style="font-family:宋体;font-size:12pt;">【样例输出】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;">55</span>
<span style="font-family:宋体;font-size:12pt;">【数据规模】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;">100%</span><span style="font-family:宋体;font-size:12pt;">的数据，</span><span style="font-family:宋体;font-size:12pt;">n</span><span style="font-family:宋体;font-size:12pt;">≤<span>10000</span></span>
<span style="font-family:宋体;font-size:12pt;">【样例解释】</span><span style="font-size:12pt;"></span>
<span style="font-size:12pt;"><span> </span><span> </span>1+2+3+4+5+6+7+8+9+10=55</span>