Question

How to find the floor and ceiling of the value N in an unsorted array with C

Answer 1

#include <stdio.h>
#include <limits.h>

void findFloorAndCeil(const int arr[], int size, int N, int *floorval, int *ceilval) {
    *floorval = INT_MIN;
    *ceilval = INT_MAX;

    for (int i = 0; i < size; ++i) {
        int num = arr[i];
        if (num <= N && num > *floorval) {
            *floorval = num;
        }
        if (num >= N && num < *ceilval) {
            *ceilval = num;
        }
    }

    if (*floorval == INT_MIN) *floorval = -1;
    if (*ceilval == INT_MAX) *ceilval = -1;
}

int main() {
    int arr[] = {4, 10, 8, 2, 6, 9, 1};
    int size = sizeof(arr) / sizeof(arr[0]);
    int N = 5;

    int floorval, ceilval;
    findFloorAndCeil(arr, size, N, &floorval, &ceilval);

    if (floorval == -1)
        printf("floor: None\n");
    else
        printf("floor: %d\n", floorval);

    if (ceilval == -1)
        printf("ceil: None\n");
    else
        printf("ceil: %d\n", ceilval);

    return 0;
}

 
 
/*
run:
 
floor: 4
ceil: 6
 
*/

 

 

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