Leetcode|二分搜索应用|1011. 在 D 天内送达包裹的能力

class Solution {
public:
    int shipWithinDays(vector<int>& weights, int days) {
        // 确定范围[minC, maxC], minC是数组中最大元素，maxC是数组累加值
        int minC = INT_MIN;
        int maxC = 0;
        for (auto& weight : weights) {
            maxC += weight;
            // 注意minC是数组中最大元素
            if (weight > minC) minC = weight;
        }
        int left = minC;
        int right = maxC;
        while (left <= right) {
            int mid = left + (right - left) / 2;
            // 注意边界控制
            int day = 1;
            int cap = mid;
            for (int i = 0; i < weights.size(); i++) {
                // 若加入当前元素过载，则day++，新增的day算当前开始
                if (cap - weights[i] < 0) {
                    day++;
                    cap = mid;
                }
                // 容量减少需要放在判断后面
                cap -= weights[i];
                if (day > days) {
                    left = mid + 1;
                    break;
                }
                if (i == weights.size() - 1) {
                    right = mid - 1;
                    minC = mid;
                }
            }
        }
        return minC;
    }
};