class Solution {public:    int maximumGap(vector<int> &num) {        int size = num.size();        if (size < 2) {            return 0;        }        int maxVal = *max_element(num.begin(), num.end());        int minVal = *min_element(num.begin(), num.end());        int gap = (maxVal - minVal - 1) / (size - 1) + 1; // ceiling function        int bucketSize = (maxVal - minVal) / gap;        vector<int> minBucket(bucketSize, INT_MAX);        vector<int> maxBucket(bucketSize, INT_MIN);        for (int i = 0; i < size; i++) {            if (num[i] == minVal || num[i] == maxVal) {                continue;            }            int idx = (num[i] - minVal) / gap;            minBucket[idx] = min(minBucket[idx], num[i]);            maxBucket[idx] = max(maxBucket[idx], num[i]);        }        int maxGap = INT_MIN;        int prev = minVal;        for (int i = 0; i < bucketSize; i++) {            if (minBucket[i] != INT_MAX) {                maxGap = max(maxGap, minBucket[i] - prev);                prev = maxBucket[i];            }        }        maxGap = max(maxGap, maxVal - prev);        return maxGap;    }};