Wood Cut

Given n pieces of wood with length L[i] (integer array). Cut them into small pieces to guarantee you could have equal or more than k pieces with the same length. What is the longest length you can get from the n pieces of wood? Given L & k, return the maximum length of the small pieces.

考察 Binary Search. 本题是二分搜索可行解。如果 长度len 为可行解那么 1~ len - 1一定是可行解。当 len 不是可行解那么len + 1 ... 一定不是可行解。因此可行解满足二分查找的条件。题目要求的是找到最大可行解，因此是二分搜索最大可行解。

注意：题目没说每一wood都需要使用，因此其解的取值范围为 1 ~ max, 其中max 为L的最大值。

public class Solution {
    public int woodCut(int[] L, int k) {
        int max = 0;
        for (int i = 0; i < L.length; i++) {
            max = Math.max(max, L[i]);
        }

        int start = 1, end = max;
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            if (check(L, mid, k)) {
                start = mid;
            } else {
                end = mid;
            }
        }
        if (check(L, end, k)) {
            return end;
        }
        if (check(L, start, k)) {
            return start;
        }
        return 0;
    }

    boolean check(int[] A, int len, int k) {
        int count = 0;
        for (int i = 0; i < A.length; i++) {
            count = count + A[i] / len;
        }
        if (count >= k) {
            return true;
        } else {
            return false;
        }
    }
}