题目

题目链接：
https://www.nowcoder.com/practice/707d98cee255448c838c76918a702be0

核心

 二分查找

Java代码

import java.util.*;public class Solution {/*** 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可*** @param a int整型一维数组* @param k int整型* @return int整型*/public int cutWood (ArrayList<Integer> ll, int k) {if (ll == null || ll.size() == 0) return 0;int[] a = new int[ll.size()];for(int i=0;i<ll.size();i++){a[i] = ll.get(i);}int L = 1; //数据合法的情况下，长度为1的是最多int R = 0;long total = 0;for (int i : a) {total += i;R = Math.max(R, i);}if (total < k) return 0;while (L < R) {int m = L + (R - L + 1) / 2;long cur = binarySearch(a, m);if (cur < k) {R = m - 1;} else {L = m;}}return L;}public long binarySearch(int[] arr, int m) {long cnt = 0;for (int i : arr) {cnt += i / m;}return cnt;}
}

Go代码

package main/*** 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可*** @param a int整型一维数组* @param k int整型* @return int整型*/
func cutWood(a []int, k int) int {if a == nil || len(a) == 0 {return 0}L := 1 //数据合法的情况下，长度为1的时候是能切最多数量的R := 0total := 0for _, t := range a {total += tif t > R {R = t}}if total < k {return 0 //数据不合法}for L < R {m := L + (R-L+1)/2cur := binarySearch(a, m)if cur < k {R = m - 1} else {L = m}}return L
}func binarySearch(arr []int, m int) int {cnt := 0for _, t := range arr {cnt += t / m}return cnt
}

C++代码

class Solution {public:/*** 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可*** @param a int整型vector* @param k int整型* @return int整型*/int cutWood(vector<int>& a, int k) {if (a.size() == 0)return 0;int L = 1; //数据合法的情况下，长度为1能切到最多数量的k【假设k是变动的】int R = 0;int total = 0;for (int i = 0; i < a.size(); i++) {int cur = a[i];total += cur;if (cur > R) {R = cur;}}while (L < R) {int m = L + (R - L + 1) / 2;int cur = binarySearch(a, m);if (cur < k) {R = m - 1;} else {L = m;}}return L;}int binarySearch(vector<int>& arr, int m) {int cnt = 0;for (int i = 0; i < arr.size(); i++) {cnt += arr[i] / m;}return cnt;}
};