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前言
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一、力扣739. 每日温度
class Solution {
public int[] dailyTemperatures(int[] temperatures) {
Deque<Integer> deq = new LinkedList<>();
int n = temperatures.length;
int[] res = new int[n];
deq.offerLast(0);
for(int i = 1; i < n; i ++){
if(temperatures[i] < temperatures[deq.peekLast()]){
deq.offerLast(i);
}else{
while(!deq.isEmpty() && temperatures[i] > temperatures[deq.peekLast()]){
int idx = deq.pollLast();
res[idx] = i - idx;
}
deq.offerLast(i);
}
}
return res;
}
}
二、力扣496. 下一个更大元素 I
class Solution {
public int[] nextGreaterElement(int[] nums1, int[] nums2) {
int[] res = new int[nums1.length];
Arrays.fill(res,-1);
Deque<Integer> deq = new LinkedList<>();
Map<Integer,Integer> map = new HashMap<>();
for(int i = 0; i < nums1.length; i ++){
map.put(nums1[i], i);
}
deq.offerLast(0);
for(int i = 1; i < nums2.length; i ++){
if(nums2[i] < nums2[deq.peekLast()]){
deq.offerLast(i);
}else{
while(!deq.isEmpty() && nums2[i] > nums2[deq.peekLast()]){
int idx = deq.pollLast();
if(map.containsKey(nums2[idx])){
int cur = map.get(nums2[idx]);
res[cur] = nums2[i];
}
}
deq.offerLast(i);
}
}
return res;
}
}
三、力扣503. 下一个更大元素 II
class Solution {
public int[] nextGreaterElements(int[] nums) {
int n = nums.length;
int[] arr = new int[n];
Arrays.fill(arr, -1);
int[] temp = new int[2*n];
for(int i = 0; i < 2*n; i ++){
temp[i] = nums[i%n];
}
Deque<Integer> deq = new LinkedList<>();
deq.offerLast(0);
for(int i = 1; i < 2*n; i ++){
if(temp[i] < temp[deq.peekLast()]){
deq.offerLast(i);
}else{
while(!deq.isEmpty() && temp[i] > temp[deq.peekLast()]){
int idx = deq.pollLast();
arr[idx % n] = temp[i];
}
deq.offerLast(i);
}
}
return arr;
}
}
四、力扣42. 接雨水
class Solution {
public int trap(int[] height) {
Deque<Integer> deq = new LinkedList<>();
int sum = 0;
deq.offerLast(0);
if(height.length == 2){
return 0;
}
for(int i = 1; i < height.length; i ++){
int pre = height[deq.peekLast()];
if(height[i] < pre){
deq.offerLast(i);
}else if(pre == height[i]){
deq.pollLast();
deq.offerLast(i);
}else{
while(!deq.isEmpty() && height[i] > pre){
int mid = height[deq.pollLast()];
if(!deq.isEmpty()){
int p = deq.peekLast();
int h = Math.min(height[p], height[i]) - mid;
int c = i - p - 1;
if(h*c > 0){
sum += h*c;
}
pre = height[deq.peekLast()];
}
}
deq.offerLast(i);
}
}
return sum;
}
}
五、力扣84. 柱状图中最大的矩形
class Solution {
public int largestRectangleArea(int[] heights) {
int res = 0;
Deque<Integer> deq = new LinkedList<>();
int[] arr = new int[heights.length + 2];
arr[0] = 0;
arr[arr.length-1] = 0;
for(int i = 0; i < heights.length; i ++){
arr[i+1] = heights[i];
}
deq.offerLast(0);
if(heights.length == 1){
return heights[0];
}
for(int i = 1; i < arr.length; i ++){
int right = arr[deq.peekLast()];
if(arr[i] >= right){
deq.offerLast(i);
}else{
while(arr[i] < arr[deq.peekLast()]){
int mid = deq.pollLast();
int pre = deq.peekLast();
int w = i - pre - 1;
int h = arr[mid];
res = Math.max(res, h*w);
}
deq.offerLast(i);
}
}
return res;
}
}