LeetCode-最小区间

美好的8月从一到困难破坏

这个题还是一头雾水，只能看官方题解了

class Solution {
    public int[] smallestRange(List> nums) {
        int rangeLeft = 0, rangeRight = Integer.MAX_VALUE;
        int minRange = rangeRight - rangeLeft;
        int max = Integer.MIN_VALUE;
        int size = nums.size();
        int[] next = new int[size];
        PriorityQueue priorityQueue = new PriorityQueue(new Comparator() {
            public int compare(Integer index1, Integer index2) {
                return nums.get(index1).get(next[index1]) - nums.get(index2).get(next[index2]);
            }
        });
        for (int i = 0; i < size; i++) {
            priorityQueue.offer(i);
            max = Math.max(max, nums.get(i).get(0));
        }
        while (true) {
            int minIndex = priorityQueue.poll();
            int curRange = max - nums.get(minIndex).get(next[minIndex]);
            if (curRange < minRange) {
                minRange = curRange;
                rangeLeft = nums.get(minIndex).get(next[minIndex]);
                rangeRight = max;
            }
            next[minIndex]++;
            if (next[minIndex] == nums.get(minIndex).size()) {
                break;
            }
            priorityQueue.offer(minIndex);
            max = Math.max(max, nums.get(minIndex).get(next[minIndex]));
        }
        return new int[]{rangeLeft, rangeRight};
    }
}

class Solution {
    public int[] smallestRange(List> nums) {
        int size = nums.size();
        Map> indices = new HashMap>();
        int xMin = Integer.MAX_VALUE, xMax = Integer.MIN_VALUE;
        for (int i = 0; i < size; i++) {
            for (int x : nums.get(i)) {
                List list = indices.getOrDefault(x, new ArrayList());
                list.add(i);
                indices.put(x, list);
                xMin = Math.min(xMin, x);
                xMax = Math.max(xMax, x);
            }
        }

        int[] freq = new int[size];
        int inside = 0;
        int left = xMin, right = xMin - 1;
        int bestLeft = xMin, bestRight = xMax;

        while (right < xMax) {
            right++;
            if (indices.containsKey(right)) {
                for (int x : indices.get(right)) {
                    freq[x]++;
                    if (freq[x] == 1) {
                        inside++;
                    }
                }
                while (inside == size) {
                    if (right - left < bestRight - bestLeft) {
                        bestLeft = left;
                        bestRight = right;
                    }
                    if (indices.containsKey(left)) {
                        for (int x: indices.get(left)) {
                            freq[x]--;
                            if (freq[x] == 0) {
                                inside--;
                            }
                        }
                    }
                    left++;
                }
            }
        }

        return new int[]{bestLeft, bestRight};
    }
}