Given a list of daily temperatures T, return a list such that, for each day in the input, tells you how many days you would have to wait until a warmer temperature. If there is no future day for which this is possible, put 0 instead.

For example, given the list of temperatures T = [73, 74, 75, 71, 69, 72, 76, 73], your output should be [1, 1, 4, 2, 1, 1, 0, 0].

Note: The length of temperatures will be in the range [1, 30000]. Each temperature will be an integer in the range [30, 100].

Notes:

1
2
3

T = [73, 74, 75, 71, 69, 72, 76, 73]
S = []
O = [ 0,  0,  0,  0,  0,  0,  0,  0]

Solution:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

class Solution {
    public int[] dailyTemperatures(int[] input) {
        Stack<Integer> stack = new Stack<>();
        int[] output = new int[input.length];
        for (int i = input.length - 1; i >= 0; i--) {
            int current = input[i];
            while (!stack.empty() && (input[stack.peek()] <= current)) {
                stack.pop();
            }
            output[i] = stack.empty() ? 0: stack.peek() - i;
            stack.add(i);
        }

        return output;
    }
}