739. Daily Temperatures - LeetCode

Question

739. Daily Temperatures

Solution

题目大意：比今天温度还要高还需要几天

思路：笨方法实现，每次遍历未来几天，比今天温度高，就坐标减

Java实现：

public int[] dailyTemperatures(int[] temperatures) {int[] ans = new int[temperatures.length];for (int i = 0; i<temperatures.length; i++) {int highIdx = i;for (int j=i+1; j<temperatures.length; j++) {if (temperatures[j] > temperatures[i]) {highIdx = j;break;}}ans[i] = highIdx - i;}return ans;
}

Ref

别人实现高效的方法

https://leetcode.com/problems/daily-temperatures/discuss/109832/Java-Easy-AC-Solution-with-Stack

Stack

public int[] dailyTemperatures(int[] temperatures) {Stack<Integer> stack = new Stack<>();int[] ret = new int[temperatures.length];for(int i = 0; i < temperatures.length; i++) {while(!stack.isEmpty() && temperatures[i] > temperatures[stack.peek()]) {int idx = stack.pop();ret[idx] = i - idx;}stack.push(i);}return ret;
}

Array

public int[] dailyTemperatures(int[] temperatures) {int[] stack = new int[temperatures.length];int top = -1;int[] ret = new int[temperatures.length];for(int i = 0; i < temperatures.length; i++) {while(top > -1 && temperatures[i] > temperatures[stack[top]]) {int idx = stack[top--];ret[idx] = i - idx;}stack[++top] = i;}return ret;
}