floorandceil.java

public class floorandceil {
    static int findFloor(int[] arr, int n, int x) {
        int low = 0, high = n - 1;
        int ans = -1;

        while (low <= high) {
            int mid = (low + high) / 2;
            
            if (arr[mid] <= x) {
                ans = arr[mid];
               
                low = mid + 1;
            } else {
                high = mid - 1; 
            }
        }
        return ans;
    }

    static int findCeil(int[] arr, int n, int x) {
        int low = 0, high = n - 1;
        int ans = -1;

        while (low <= high) {
            int mid = (low + high) / 2;
           
            if (arr[mid] >= x) {
                ans = arr[mid];
                high = mid - 1;
            } else {
                low = mid + 1; 
            }
        }
        return ans;
    }
    public static int[] getFloorAndCeil(int[] arr, int n, int x) {
        int f = findFloor(arr, n, x);
        int c = findCeil(arr, n, x);
        return new int[] {f, c};
    }
    public static void main(String[] args) {
        int[] arr = {3, 4, 4, 7, 8, 10};
        int n = 6, x = 5;
        int[] ans = getFloorAndCeil(arr, n, x);
        System.out.println("The floor and ceil are: " + ans[0]
                           + " and " + ans[1]);
    }
    
}

//time complexity -O(log n)
//space complexity -O(1)