Time: 25 ms (26.72%) | Memory: 65.8 MB (7.76%) - LeetSync

Author: Odonata971

3741-reschedule-meetings-for-maximum-free-time-ii/reschedule-meetings-for-maximum-free-time-ii.java

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+
+class Solution {
+ public int maxFreeTime(int eventTime, int[] startTime, int[] endTime) {
+ int n = startTime.length;
+ 
+ // Original gaps
+ List<int[]> gaps = new ArrayList<>();
+ 
+ // gap before first meeting
+ if (startTime[0] > 0) {
+ gaps.add(new int[]{0, startTime[0]});
+ }
+ 
+ // gaps between meetings
+ for (int i = 1; i < n; i++) {
+ if (startTime[i] > endTime[i - 1]) {
+ gaps.add(new int[]{endTime[i - 1], startTime[i]});
+ }
+ }
+ 
+ // gap after last meeting
+ if (eventTime > endTime[n - 1]) {
+ gaps.add(new int[]{endTime[n - 1], eventTime});
+ }
+ 
+ // Sort gaps by size descending to optimize search (early termination)
+ gaps.sort((a, b) -> Integer.compare(b[1] - b[0], a[1] - a[0]));
+ 
+ // Get max original gap
+ int maxGap = gaps.isEmpty() ? 0 : gaps.get(0)[1] - gaps.get(0)[0];
+ 
+ // Try rescheduling each meeting
+ for (int i = 0; i < n; i++) {
+ int dur = endTime[i] - startTime[i];
+ 
+ // Remove current meeting and create merged gap
+ int left = (i == 0) ? 0 : endTime[i - 1];
+ int right = (i == n - 1) ? eventTime : startTime[i + 1];
+ int mergedGap = right - left;
+ 
+ // Case 1: Place meeting back in the merged gap itself
+ if (mergedGap >= dur) {
+ maxGap = Math.max(maxGap, mergedGap - dur);
+ }
+ 
+ // Case 2: Try placing this meeting in any other gap
+ // Optimization: early termination since gaps are sorted by size
+ for (int[] gap : gaps) {
+ int gapLen = gap[1] - gap[0];
+ 
+ // If this gap is too small, all following gaps will be too small
+ if (gapLen < dur) {
+ break;
+ }
+ 
+ // Check if this gap overlaps with the merged gap
+ boolean overlapsMerged = !(gap[1] <= left || gap[0] >= right);
+ 
+ if (!overlapsMerged) {
+ // Independent gap - we can place the meeting here
+ maxGap = Math.max(maxGap, mergedGap);
+ break; // Found optimal solution for this meeting
+ }
+ }
+ }
+ 
+ return maxGap;
+ }
+}