Leetcode-27:Remove Element

问题描述：

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 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.

问题示例

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

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

我的答案

int removeElement(vector<int>& nums, int val) {
    int size = nums.size();
    for (int i=0; i<size; i++) {
        if(nums[i] == val){
            swap(nums[i], nums[size-1]);
            i--;
            size--;
        }
    }
    nums.resize(size);
    return size;
}

其他高效答案

//更快的删除尾结点
int removeElement(vector<int>& nums, int val) {    
        int sz = nums.size();
        if( sz == 0 ) return 0;
        while( nums[sz-1] == val && sz >0 ) sz--;
        for( int i=0; i<sz; ++i){
            if( nums[i] == val ) {
                nums[i] = nums[sz-1];
                sz--;
                while( nums[sz-1] == val ) sz--;
            }
        }
        nums.resize(sz);
        return sz;
    
    }

赏

谢谢你请我吃糖果

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