亲测wa了无数遍得到的板子....
模板:
int l=0,r=n,ans=inf; while(l<=r-1) { int mid=(l+r)>>1; int midmid=(r+mid)>>1; int ans1=judge(mid),ans2=judge(midmid); if(ans1<=ans2) ans=min(ans,ans1),r=midmid; else ans=min(ans,ans2),l=mid; }