Leetcode题解14 27. Remove Element

Given an array and a value, remove all instances of that value in place and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

Example:

Given input array nums = [3,2,2,3], val = 3

Your function should return length = 2, with the first two elements of nums being 2.

用hashmap存储数组中值不是val的所有元素，键为元素值，值为元素出现次数。轻松搞定。

public static int removeElement(int[] nums, int val) {
HashMap<Integer, Integer> hashMap = new HashMap<Integer, Integer>();
int count = 0;
int temp;
for (int i = 0; i < nums.length; i++) {
if (nums[i] != val) {
if (hashMap.get(nums[i]) != null) {
temp = hashMap.get(nums[i]);
hashMap.put(nums[i], ++temp);
} else {
hashMap.put(nums[i], 1);
}
}
}
Iterator it = hashMap.keySet().iterator();
while (it.hasNext()) {
int key = (int) it.next();
for (int i = 0; i < hashMap.get(key); i++) {
nums[count] = key;
count++;
}
}
return count;
}