Maximum Gap

#1: sort

class Solution {
public:
    int maximumGap(vector<int>& nums) {
        int n = nums.size();
        if (n < 2) return 0;
        int res = 0;
        sort(nums.begin(), nums.end());
        for (int i = 1; i < n; i++) {
            int d = nums[i] - nums[i-1];
            res = res > d ? res : d;
        }
        return res;
    }
};

#2: bucket sort 答案解法

class Solution {
public:
    int maximumGap(vector<int>& nums) {
        int n = nums.size();
        if (n < 2) return 0;
        int min = nums[0], max = nums[0];
        for (int i = 1; i < n; i++) {
            min = nums[i] < min ? nums[i] : min;
            max = nums[i] > max ? nums[i] : max;
        }
        int p = (max - min) / (n - 1) + 1; //平均差值
        int b = (max - min) / p + 1; // 桶个数
        vector<vector<int>> bucket(b, vector<int>());
        vector<int> maxs(b, -1);
        vector<int> mins(b, max);
        for (int i = 0; i < n; i++) {
            int j = (nums[i] - min)/p;
            bucket[j].push_back(nums[i]);
            maxs[j] = maxs[j] > nums[i] ? maxs[j] : nums[i];
            mins[j] = mins[j] < nums[i] ? mins[j] : nums[i];
        }
        int res = p - 1;
        for (int s = b - 1, i = b - 2; i >= 0; i--) {
            if (bucket[i].empty()) continue;
            int diff = mins[s] - maxs[i];
            res = res > diff ? res : diff;
            s = i;
        }
        return res;
    }
};