Problem 1001Duplicate Pair

Accept: 5413    Submit: 25842
Time Limit: 1000 mSec    Memory Limit : 65536 KB

 Problem Description

An array of length n, with address from 1 to n inclusive, contains entries from the set {1,2,...,n-1} and there's exactly two elements with the same value. Your task is to find out the value.

 Input

Input contains several cases.
Each case includes a number n (1<n<=10^6), which is followed by n integers.
The input is ended up with the end of file.

 Output

Your must output the value for each case, one per line.

 Sample Input

21 141 2 3 2

 Sample Output

12

 Source

IBM Challenge 2004.1

int sum[1000000]={0};
int main(int argc, const char * argv[]) {
    long i,j,n;
    while(scanf("%ld",&i)!=EOF){
        for(j=0;j

之前疯狂超时报错，后规范写法将

while(scanf("%ld",&i))

改为

while(scanf("%ld",&i)!=EOF)

最终完成