codeforce Gym 100500F Door Lock （二分）

#include<cstdio>

using namespace std;
typedef long long ll;

int main()
{
int T;
scanf("%d",&T);
for(int k = 1; k <= T; k++){
ll n,m;
scanf("%I64d%I64d",&n,&m);
ll L = 0, R = n;
ll mid , b1, b2;
while(L < R){
mid = (L + R) >> 1;
b1 = (mid*(mid+1))>>1;
if(m <= b1) {
R = mid;
continue;
}
b2 = ((mid+2)*(mid+1))>>1;
if(b2 < m) {
L = mid;
continue;
}
break;
}
if(L == R) mid = L;
printf("Case %d: %I64d %I64d\n",k,mid,m-b1-1);
}
return 0;
}