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1 #include <cstdio> 2 3 int main(int argc, char const *argv[]) 4 { 5 long long n; 6 while(~scanf("%d",&n)){ 7 printf("%d\n\n", (1+n)*n/2); 8 } 9 return 0; 10 }
hdu_1001
原文地址：http://www.cnblogs.com/takeoffyoung/p/4190389.html
