Leetcode刷题-Remove Element

秒速五厘米 2023-01-08 12:29 61阅读 0赞

# 题目 #

https://leetcode-cn.com/problems/remove-element/

Given an array nums and a value val, 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 by modifying the input array in-place with O(1) extra memory.

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

# 代码 #

class Solution {
        public int removeElement(int[] nums, int val) {
            int i = 0;
            for (; i < nums.length; i++) {
                if (val == nums[i]) {
                    break;
                }
            }
            int cur = i++;
            for (; i < nums.length; i++) {
                if (val != nums[i]) {
                    nums[cur++] = nums[i];
                }
            }
            return cur;
        }
    }

# 结果 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NuZGF5WVU_size_16_color_FFFFFF_t_70]

# 其他解法 #

class Solution {
        public int removeElement(int[] nums, int val) {
            int i = 0;
            int n = nums.length - 1;
            while (i <= n) {
                // drd notes: 找到某个等于val的
                while (i <= n && nums[i] != val) {i++;}
                // drd notes: 从后往前，找到首个 不等于val的
                while (n >= i && nums[n] == val) {n--;}
                if (i < n) {
                    nums[i++] = nums[n--];
                } else {
                    return i;
                }
            }
            return i;
        }
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NuZGF5WVU_size_16_color_FFFFFF_t_70]: /images/20221119/84dea9c543484adf9b5d6fac40123169.png