Remove Element

class Solution {
public:
int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
int len = 0;
for (int i = 0; i < n; i++)
{   
    if (A[i] != elem)
        A[len++] = A[i];
}
return len;
}
};

public class Solution {
 public int removeElement(int[] A, int elem) {
    int len=A.length;
    for(int i=0;i<len;){
        if(A[i]==elem)
            A[i]=A[--len];
        else
            i++;            
    }
    return len;
 }

}

    int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    int i=-1,j;
    for (j=0;j<n;j++)
    {
        if (A[j] != elem)
        {
            A[++i]=A[j];                
        }
    }
    return i+1;
}

class Solution {
public:
   int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    int len = 0;
    for(int i=0;i<n;i++)
    {
        if( A[i] != elem)
            A[len++] = A[i];
    }
    return len;
 }

};

keep the order of the array

int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    int retVal =0;
    int ix = 0; 
    for(int i=0; i<n; i++){
        if(A[ix] == elem){
            for(int j = ix; j<n-1; j++){
                *(A+j) = *(A+j+1);
            }
            ix--;
        }
        else{
            retVal++; 
        }
        ix++;
    }
    return retVal; 
}

public class Solution {

public int removeElement(int[] A, int elem) {
    if(A == null || A.length == 0)
        return 0;
    int size = A.length;
    for(int i = A.length-1;i>=0;i--){
        if(A[i] == elem){
            A[i] = A[--size];
        }
    }
    return size;
}

}

int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    int head = 0, tail = n-1;
    for (int i = n-1; i >= 0; i--) {
        if (A[i] == elem) {
            continue;
        }
        A[tail--] = A[i];
    }

    for (int i = tail+1; i < n; i++) {
        A[head++] = A[i];
    }

    return head;
}

class Solution {

public:

int removeElement(int A[], int n, int elem) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    int i; 
    int k1, k2; 
    k1=0; k2=0; 
    while(k2<=n-1)
    {
     if(A[k2]==elem) k2++; 
     else 
      { A[k1]=A[k2]; k1++; k2++; }    
    }
    return k1; 
}

};

int removeElement(int A[], int n, int elem) {
    if (n <= 0) return 0;
    int num = 0;
    while (A[num] != elem && num < n) num++;
    if (num == n) return n;
    for (int i = num + 1; i < n; ++i) {
        if (A[i] != elem) {
            A[num++] = A[i];
        }
    }
    return num;    
}

Since there's no need to actually 'free' the unused memory, you just have to pull all the valid values form the end of the array to the places where the target element is; then, re-check that slot in case in was a target element too.

class Solution {
public:
    int removeElement(int A[], int n, int elem) {
        for(int i = 0; i < n; i++){
            if(A[i] == elem)
                A[i--] = A[--n];
        }
        return n;
    }
};