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DegreeOfArray.java
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/
DegreeOfArray.java
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import java.util.Collections;
import java.util.HashMap;
/*
* 数组的度 leetCode-697
* */
public class DegreeOfArray {
private static void findShortestSubArray(int[] arr) {
if (arr == null || arr.length == 0) {
System.out.print("error input!");
return;
}
HashMap<Integer, Integer> left = new HashMap<>();
HashMap<Integer, Integer> right = new HashMap<>();
HashMap<Integer, Integer> count = new HashMap<>();
for (int i = 0; i < arr.length; i++) {
if (!left.containsKey(arr[i])) {
left.put(arr[i], i);
}
right.put(arr[i], i);
count.put(arr[i], count.getOrDefault(arr[i], 0) + 1);
}
int degree = Collections.max(count.values());
int minLength = Integer.MAX_VALUE;
int length = 0;
for (int i = 0; i < arr.length; i++) {
if (count.get(arr[i]) == degree) {
// System.out.print("left: " + left.get(arr[i]));
// System.out.print(",right: " + right.get(arr[i]));
length = right.get(arr[i]) - left.get(arr[i]) + 1;
if (minLength > length) {
minLength = length;
}
}
}
System.out.print("length: " + minLength);
}
public static void main(String[] args) {
int[] arr = new int[]{1, 2, 2, 3, 1};
findShortestSubArray(arr);
}
}