632. 最小区间

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class Solution {public int[] smallestRange(List<List<Integer>> nums) {int size = nums.size();Map<Integer, List<Integer>> indices = new HashMap<Integer, List<Integer>>();int xMin = Integer.MAX_VALUE, xMax = Integer.MIN_VALUE;for (int i = 0; i < size; i++) {for (int x : nums.get(i)) {List<Integer> list = indices.getOrDefault(x, new ArrayList<Integer>());list.add(i);  // 下标存入进去indices.put(x, list);  // 存放元素 - 下标数组[]xMin = Math.min(xMin, x);  // 所有元素的最小值、最大值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++; // 窗口右移动if (indices.containsKey(right)) {for (int i : indices.get(right)) {  // i值为小数组下标freq[i]++;if (freq[i] == 1) {  // 小数组数inside++;}}while (inside == size) {  // k个列表if (right - left < bestRight - bestLeft) {bestLeft = left;bestRight = right;}if (indices.containsKey(left)) {for (int i: indices.get(left)) {freq[i]--;if (freq[i] == 0) {inside--;}}}left++;}}}return new int[]{bestLeft, bestRight};}
}