I need to find Big O and provide an explanation

1.

int sum = 0;

for (int j = n; j > 0; j /= 2){

for (int k = 0; k < j; k++) {

sum += 1; }

}

2. for (int i = 0 ; i < n ; i++) {

int j = 2 * i ;

while (j < n) {

j = j + 2 ;

}

}