第三题优点哈夫曼树的意思。 public int minEffort(ArrayList<Integer> cases) { // write code here PriorityQueue<Integer> minHeap = new PriorityQueue<>(new Comparator<Integer>() { @Override public int compare(Integer o1, Integer o2) { return o1-o2; } }); int result = 0; minHeap.addAll(cases); while(minHeap.size()>1){ int x1 = minHeap.poll(); int x2 = minHeap.poll(); result += x1; result += x2; minHeap.add(x1+x2); } return result; }