• 双指针-快慢指针
• 摩尔投票算法

1.双指针-快慢指针

// 时间复杂度：O(n)
// 空间复杂度：O(1)
class Solution {
public:
int removeElement(vector<int>& nums, int val) {
int slowIndex = 0;
for (int fastIndex = 0; fastIndex < nums.size(); fastIndex++) {
if (val != nums[fastIndex]) {
nums[slowIndex++] = nums[fastIndex];
 }
 }
return slowIndex;
 }
};

2.摩尔投票算法（求众数）

// 摩尔投票算法
int majorityElement(int* nums, int numsSize) {
    int count = 0;
    int candidate = 0;

    for (int i = 0; i < numsSize; i++) {
        if (count == 0) {
            candidate = nums[i];
        }
        count += (nums[i] == candidate) ? 1 : -1;
    }
    return candidate;
}