class Solution {

public int[] assignTasks(int[] servers, int[] tasks) {

int[] res = new int[tasks.length];

// [weight, index]

Queue<int[]> available = new PriorityQueue<>((a, b) -> a[0] == b[0] ? a[1] - b[1] : a[0] - b[0]);

for (int i = 0; i < servers.length; i++)

available.add(new int[] { servers[i], i });

int time = 0;

int nextTask = 0;

// [weight, index, done time]

Queue<int[]> unavail = new PriorityQueue<>((a, b) -> a[2] - b[2]);

while (nextTask < tasks.length) {

// release available servers

while (!unavail.isEmpty() && unavail.peek()[2] <= time) {

int[] curr = unavail.poll();

available.add(new int[] { curr[0], curr[1] });

}

// assign task(s)

while (!available.isEmpty() && nextTask < time && nextTask != tasks.length) {

int[] curr = available.poll();

unavail.add(new int[] { curr[0], curr[1], time + tasks[nextTask] });

res[nextTask++] = curr[1];

}

// advance time

if (available.isEmpty())

time = unavail.peek()[2];

else

time++;

}

return res;

}

}