矩形内船只的数目

// 使用Java Stream的题解代码和注释

/*
 * 题目思路：
 * 由于Java Stream更适用于处理集合和数据流，本题目更适合递归划分和直接调用hasShips方法。
 * 由于题目特性，不适合使用Stream进行解决，此处提供类似的递归划分思路。
 */

class Solution {
    public int countShips(Sea sea, int[] topRight, int[] bottomLeft) {
        // Stream不适合此问题的解法，依然使用递归
        if (topRight[0] < bottomLeft[0] || topRight[1] < bottomLeft[1]) {
            return 0;
        }
        if (!sea.hasShips(topRight, bottomLeft)) {
            return 0;
        }
        if (topRight[0] == bottomLeft[0] && topRight[1] == bottomLeft[1]) {
            return 1;
        }
        int midX = (topRight[0] + bottomLeft[0]) / 2;
        int midY = (topRight[1] + bottomLeft[1]) / 2;
        return countShips(sea, new int[]{midX, midY}, bottomLeft) +
               countShips(sea, topRight, new int[]{midX + 1, midY + 1}) +
               countShips(sea, new int[]{midX, topRight[1]}, new int[]{bottomLeft[0], midY + 1}) +
               countShips(sea, new int[]{topRight[0], midY}, new int[]{midX + 1, bottomLeft[1]});
    }
}