Description
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.
You couldn't cut wood into float length.
If you couldn't get >= k pieces, return 0.
Example
Example 1
Input:
L = [232, 124, 456]
k = 7
Output: 114
Explanation: We can cut it into 7 pieces if any piece is 114cm long, however we can't cut it into 7 pieces if any piece is 115cm long.
Example 2
Input:
L = [1, 2, 3]
k = 7
Output: 0
Explanation: It is obvious we can't make it.
Challenge
O(n log Len), where Len is the longest length of the wood.
Idea: The dichotomy answer method, two points up to the amount, if can be done, is increased, if not, is reduced.
public class Solution {
/**
* @param L: Given n pieces of wood with length L[i]
* @param k: An integer
* return: The maximum length of the small pieces.
*/
public int woodCut(int[] L, int k) {
int l = 1, res = 0;
int r = 0;
for (int item : L) {
r = Math.max(r, item);
}
while (l <= r) {
int mid = l + (r - l) / 2; // (l + r) / 2 may overflow
if (count(L, mid) >= k) {
res = mid;
l = mid + 1;
} else {
r = mid - 1;
}
}
return res;
}
private int count(int[] L, int len) {
int sum = 0;
for (int item : L) {
sum += item / len;
}
return sum;
}
}