Leetcode 57、插入区间

Leetcode 57、插入区间

思路：二分查找+区间合并

1. 把intervals数组添加都list里面
2. 调用getIndex使用二分查找法找到newInterval应该插入的位置
3. 把newInterval插入到list对应的位置
4. 对list进行区间合并，如果i和i + 1有交叉，则进行合并
5. 把list转成int[][],返回结果

class Solution {
    public int[][] insert(int[][] intervals, int[] newInterval) {
        if(intervals.length == 0) {
            int[][] result = new int[1][2];
            result[0] = newInterval;
            return result;
        }

        List<int[]> list = new ArrayList<>();
        for(int[] interval : intervals) {
            list.add(interval);
        }

        int index = getIndex(list, newInterval);
        list.add(index, newInterval);

        for(int i = 0; i < list.size() - 1; i++) {
            if(list.get(i + 1)[0] <= list.get(i)[1]) {
                int[] curr = list.get(i);
                curr[1] = Math.max(list.get(i + 1)[1], list.get(i)[1]);
                list.set(i, curr);
                list.remove(i + 1);
                i--;
            }
        }

        int[][] result = new int[list.size()][2];
        for(int i = 0; i < list.size(); i++) {
            result[i] = list.get(i);
        }

        return result;
    }

    public int getIndex(List<int[]> list, int[] newInterval) {
        int left = 0, right = list.size() - 1;
        while(left <= right) {
            int mid = (right - left) / 2 + left;
            if(list.get(mid)[0] > newInterval[0]) {
                right = mid - 1;
            }else if(list.get(mid)[0] < newInterval[0]){
                left = mid + 1;
            }else{
                return mid;
            }
        }
        return left;
    }
}