POJ3712Edges and More Edges

pku3712Edges and More Edges

 #include<cstdio>int main(){ int n,k; while(scanf("%d%d",&n,&k),!(n==0&&k==0)) { if(k==1) {printf("%d/n",0);continue;} if(2*k>n) { printf("%d/n",n*(n-1)>>1);continue;} int a=0,b=0; a=(n-1)*n/2-(n-k)*(n-k+1)/2; if(n>(k*2)) b=(k-1)*(2*k-1); printf("%d/n",a>b?a:b); }}