Binary Indexed Trees Templates

//memset c 0 before use
int c[MAXN];

//n -> update place
//v -> update value
void update(int n,int v)
{
    for(;n<=MAXN;n+=(n&-n))
        c[n]+=v;
}

//get the sum from 1 to n (BIT starts from 1)
int read(int n)
{
    int sum=0;
    for(;n>0;n-=(n&-n))
        sum+=c[n];
    return sum;
}
//if need oprate different array, use int* array

/////////////////////////////////////////////

int c[MAXX][MAXY];

//update at (x,y)
void update2D(int x,int y,int v)
{
    for(;x<=MAXX;x+=(x&-x))
        for(int i=y;i<=MAXY;i+=(i&-i))
            c[x][i]+=v;
}

//get the sum from (1,1) to (x,y)
int read2D(int x,int y)
{
    int sum=0;
    for(;x>0;x-=(x&-x))
        for(int i=y;i>0;i-=(i&-i))
            sum+=c[x][i];
    return sum;
}