代码随想录五刷day11

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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;
    }
}