Codeforces Round #655 (Div. 2) F.Omkar and Modes(交互 分治 二分)
题目n(nusingnamespacestd;constintN=2e5+10;mapmp;intn,a[N];voidask(intl,intr,int&x,int&f){printf("?%d%d\n",l,r);fflush(stdout);scanf("%d%d",&x,&f);}voiddfs(intl,intr){if(l>r){return;}intx,f;ask(l,r,x,f);