Sum Problem

Sum Problem Time Limit: 1000/500 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 77962 Accepted Submission(s): 17478 Problem Description Hey, welcome to HDOJ(Hangzhou Dianzi University Online Judge). In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + ... + n. Input The input will consist of a series of integers n, one integer per line. Output For each case, output SUM(n) in one line, followed by a blank line. You may assume the result will be in the range of 32-bit signed integer. Sample Input 1 100 Sample Output 1 5050 杭電上的題目，出現錯誤的原因是，計算過程中出現了大於32整數的結果，比如n*(n+1)/2，這樣會造成WA。 但是可以出現大於32位整數的float。把n*(n+1)/2改成(int)(n*(n+1.0)/2.0)就行了。 另外在輸出的時候一定要注意printf("%d/n/n",sum);