Leetcode 1011：在 D 天内送达包裹的能力

//执行耗时:9 ms,击败了97.62% 的Java用户
//内存消耗:45.3 MB,击败了12.84% 的Java用户
class Solution {
    public int shipWithinDays(int[] weights, int days) {
        // 确定二分查找左右边界
        int left = Integer.MIN_VALUE;
        int right = 0;
        for (int weight : weights) {
            left = Math.max(weight, left);
            right += weight;
        }
        while (left < right) {
            int mid = (left + right) / 2;
            // need 为需要运送的天数
            // cur 为当前这一天已经运送的包裹重量之和
            int need = 1, cur = 0;
            for (int weight : weights) {
                //这个地方注意判断条件
                if (cur + weight > mid) {
                    ++need;
                    cur = 0;
                }
                cur += weight;
            }
            if (need <= days) {
                right = mid;
            } else {
                //mid不应该被包含进来
                left = mid + 1;
            }
        }
        return left;
    }
}