Successful Pairs of Spells and Potions — Sort + Binary Search

# Python
import bisect, math
def successfulPairs(spells, potions, success):
    potions.sort()
    res = []
    n = len(potions)
    for s in spells:
        # Need potion >= ceil(success/s)
        threshold = math.ceil(success/s)
        idx = bisect.bisect_left(potions, threshold)
        res.append(n - idx)
    return res

// Java
public int[] successfulPairs(int[] spells, int[] potions, long success) {
    Arrays.sort(potions);
    int n=potions.length; int[] res=new int[spells.length];
    for (int i=0;i<spells.length;i++) {
        long need=(success+spells[i]-1)/spells[i]; // ceil
        int lo=0,hi=n;
        while(lo<hi){int mid=(lo+hi)/2;if(potions[mid]>=need)hi=mid;else lo=mid+1;}
        res[i]=n-lo;
    }
    return res;
}