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我试着解决nailingPlanks的例子。我做了一些代码（看下面），解决几乎所有的测试案例，除了3.我的代码返回错误的答案，但我不知道为什么。为什么NailingPlanks为随机小序列返回不正确结果的Codility？
Codlility说 “错误答案得到79预期61” 为random_small随机序列，长度=〜100
这是此试验的情况下：
int[] A = { 28, 18, 43, 15, 26, 18, 21, 49, 6, 23, 12, 18, 50, 17, 31, 21, 37, 23, 9, 22, 21, 40, 29, 10, 34, 15, 26, 11, 21, 40, 26, 38, 38, 30, 33, 20, 31, 39, 5, 47, 19, 7, 8, 18, 4, 20, 21, 33,24, 47, 33, 17, 44, 35, 49, 37, 49, 11, 14, 49, 2, 47, 6, 7,8, 46, 48, 44, 37, 38, 16, 1, 32, 45, 48, 26, 1, 9, 23, 12, 2,10, 25, 7, 6, 9, 2, 40, 44, 11, 32, 44, 13, 17, 45, 39, 32, 40,29, 16 };
int[] B = { 55, 32, 44, 48, 36, 31, 41, 81, 56, 46, 62, 68, 62, 20,39, 63, 67, 69, 58, 55, 48, 43, 30, 51, 68, 53, 54, 45, 53, 85, 31, 63, 53, 72, 77, 32, 35, 51, 21, 86, 39, 45, 23, 44, 13, 52,47, 76, 72, 73, 36, 64, 92, 59, 73, 84, 61, 24, 49, 83, 36, 89, 72, 28, 19, 56, 66, 66, 74, 69, 42, 20, 63, 64, 88, 58, 36, 28, 49, 48, 50, 36, 41, 42, 12, 26, 3, 68, 56, 30, 72, 76, 14, 39,45, 80, 57, 83, 42, 57 };
int[] C = { 55, 35, 85, 29, 52, 35, 42, 98, 11, 45, 23, 35, 100, 33,61, 42, 74, 45, 18, 44, 41, 80, 57, 20, 68, 30, 52, 22, 42, 79, 52, 76, 76, 59, 65, 40, 62, 78, 10, 94, 37, 14, 16, 35, 7, 40,42, 66, 47, 94, 66, 33, 88, 70, 97, 74, 97, 21, 28, 98, 3, 93,92, 14, 16, 92, 96, 87, 73, 76, 31, 1, 63, 89, 95, 52, 1, 18,45, 24, 3, 20, 50, 13, 12, 17, 4, 79, 87, 21, 64, 88, 25, 34,89, 77, 63, 80, 58, 32, 69, 79, 6, 33, 30, 89, 29, 68, 44, 38, 50, 90, 66, 39, 16, 35, 48, 65, 100, 33, 95, 92, 45, 23, 24,93, 18, 65, 66, 17, 4, 64, 6, 55, 98, 47, 32, 11, 31, 33, 12, 71, 61, 72, 11, 26, 93, 1, 37, 82, 23, 23, 64, 26, 34, 40,30, 66, 74, 77, 99, 8, 26, 99, 80, 77, 23, 13, 28, 90, 76, 37, 66,74, 29, 11, 82, 71, 81, 75, 37, 66, 37, 91, 13, 70, 35, 91, 81,18, 2, 24, 97, 77, 71, 21, 22, 45, 54, 62, 6, 85, 25, 72, 32,30, 88, 22, 51, 88, 83, 72, 25, 63, 48, 31, 78, 68, 90, 43, 15,28, 74, 71, 65, 40, 58, 7, 10, 81, 12, 63, 30, 18, 79, 89, 32,16, 47, 12, 97, 3, 51, 17, 1, 100, 69, 71, 77, 79, 61, 67, 32, 11, 73, 74, 74, 65, 9, 65, 9, 88, 1, 27, 54, 87, 66, 14, 73,21, 34, 37, 80, 21, 33, 29, 25, 22, 39, 18, 26, 12, 59, 70, 24, 45, 61, 98, 97, 12, 95, 81, 23, 20, 51, 29, 32, 41, 55, 55 };
我的代码：
import java.util.Arrays;
class Solution {
public static class Nail implements Comparable<Nail> {
int value = -1;
int orginalIndex = -2;
public Nail(int val, int idx) {
value = val;
orginalIndex = idx;
}
@Override
public int compareTo(Nail o) {
int dv = value - o.value;
return dv;
}
}
public static final Nail INCORECT_NAIL = new Nail(-1, -2);
public int solution(int[] A, int[] B, int[] C) {
int N = A.length;
int M = C.length;
Nail[] nails = new Nail[M];
for (int i = 0; i < C.length; i++) {
nails[i] = new Nail(C[i], i);
}
Nail[] sortedNails = Arrays.copyOf(nails, nails.length);
Arrays.sort(sortedNails);
int solution = -1;
for (int i = 0; i < N; i++) {
solution = binSearch(sortedNails, A[i], B[i], solution);
if (solution == -1)
return -1;
}
return solution + 1;
}
int binSearch(Nail[] sortedNails, int beginPlank, int endPlank, int solution) {
int M = sortedNails.length;
// jeżeli wszystkie gwoździe są poza deską to nie ma rozwiązania
if (sortedNails[sortedNails.length - 1].value < beginPlank)
return -1;
if (sortedNails[0].value > endPlank)
return -1;
int aidx = Arrays.binarySearch(sortedNails, new Nail(beginPlank,
beginPlank));
int bidx = Arrays.binarySearch(sortedNails,
new Nail(endPlank, endPlank));
int a = (aidx >= 0 ? aidx : -aidx - 1);
int b = (bidx >= 0 ? bidx : -bidx - 2);
if (b < a)
return -1;
// System.out.println(a +" - " + b);
if (sortedNails[a].value > endPlank)
return -1;
if (sortedNails[b].value < beginPlank)
return -1;
int minOrginalIndex = Integer.MAX_VALUE;
Nail currentNail = null;
while (a < M && (sortedNails[a].value <= endPlank)) {
currentNail = sortedNails[a];
if (currentNail.orginalIndex <= solution) {
return solution;
}
if (currentNail.orginalIndex < minOrginalIndex) {
minOrginalIndex = currentNail.orginalIndex;
}
a++;
}
//System.out.print(minOrginalIndex + " | ");
return minOrginalIndex;
}
}