leetcode-1011 在 D 天内送达包裹的能力

题目描述：传送带上的包裹必须在 D 天内从一个港口运送到另一个港口。

传送带上的第 i 个包裹的重量为 weights[i]。每一天，我们都会按给出重量的顺序往传送带上装载包裹。我们装载的重量不会超过船的最大运载重量。

返回能在 D 天内将传送带上的所有包裹送达的船的最低运载能力。

代码实现

class Solution {
    public int shipWithinDays(int[] weights, int days) {
        int minWeight = Integer.MIN_VALUE;
        int maxWeight = 0;
        int len = weights.length;
        for (int i = 0; i < len; i++) {
            maxWeight += weights[i];
            if (weights[i] > minWeight) {
                minWeight = weights[i];
            }
        }
        int left = minWeight;
        int right = maxWeight;
        while (left <= right) {
            int mid = left + (right - left) / 2;
            int currentDays = calculateDays(weights, mid);
            if (currentDays == days) {
                right = mid - 1;
            } else if (currentDays < days) {
                right = mid - 1;
            } else if (currentDays > days) {
                left = mid + 1;
            }
        }
        return left;
    }

    public int calculateDays(int[] weights, int weight) {
        int days = 0;
        int i = 0;
        int tmpWeight = weight;
        while (i < weights.length) {
            if (tmpWeight >= weights[i]) {
                tmpWeight -= weights[i];
                i++;
                if (i == weights.length) {
                    days++;
                }
            } else {
                tmpWeight = weight;
                days++;
            }
        }
        return days;
    }
}