739. Daily Temperatures (Medium)
https://leetcode.com/problems/daily-temperatures/
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].
Solutions
class Solution {
public int[] dailyTemperatures(int[] T) {
if (T == null || T.length == 0) {
return new int[0];
}
int[] ans = new int[T.length];
Stack<Integer> stack = new Stack<>();
for (int i = 0; i < T.length; i++) {
// also push in same temperature
if (stack.isEmpty() || T[stack.peek()] >= T[i]) {
stack.push(i);
continue;
}
// [73], 74
// [75,71,69], 72
// T[stack.peek()] < T[i]
while (!stack.isEmpty() && T[stack.peek()] < T[i]) {
int preDay = stack.pop();
ans[preDay] = i - preDay;
}
// After pop out all the lower temperatures, push in T[i]
stack.push(i);
}
return ans;
}
}