找出函数的最宽尖峰

 public static void main(String[] args) {
        //预处理左右各做一遍最长上升子串, 然后维护一个最大和即可
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] x = new int[n];
        for (int i = 0; i < n; i++) {
            x[i] = sc.nextInt();
        }
        int[] l = new int[n];
        for (int i = 1; i < n; i++) {
            if (x[i] - x[i - 1] > 0) {
                l[i] = l[i - 1] + 1;
            }
        }
        int[] r = new int[n];
        for (int i = n - 2; i >= 0; i--) {
            if (x[i] > x[i + 1]) {
                r[i] = r[i + 1] + 1;
            }
        }
        int mx = 0, ll = -1, rr = -1;
        for (int i = 0; i < n; i++) {
            if (l[i] > 0 && r[i] > 0 && l[i] + r[i] > mx) {
                mx = l[i] + r[i];
                ll = i - l[i];
                rr = i + r[i];
            }
        }
        System.out.print(ll + " " + rr);
    } 

#include<iostream>
#include<vector>

using namespace std;

int main()
{
    int n, i, num;
    vector<int> nums;

    cin >> n;
    for (i = 0; i < n; i++) {
        cin >> num;
        nums.push_back(num);
    }

    i = 0;
    int l = -1, r = -1; // 临时左右边界
    int left = -1, right = -1, max_len = -1; // 最终需要输出的最大左右边界和最大长度

    // 认为i是峰顶的下标，往左右两个方向找左右边界
    while (i < n) {
        if (l == -1) { // l == -1 表示左边界需要重新找
            l = i;
            while (l > 0 && nums[l - 1] < nums[l]) // 找左边界
                l--;
        }

        r = i;
        while (r < n - 1 && nums[r + 1] < nums[r]) // 找右边界
            r++;

        if (r > i && l < i && r - l + 1 > max_len) { // 更新最大值
            max_len = r - l + 1;
            left = l;
            right = r;
        }

        // r == i 表示没有右边界，还在上升阶段，下一个峰顶的左边界还是l，就不需要再找左边界了
        if (r != i)
            l = -1;
        i = r + 1; // 把i更新为下一个可能的峰顶
    }
    cout << left << " " << right << endl;

    return 0;
}

#include<iostream>
#include <vector>
#include <map>

using namespace std;

typedef struct __tagNode
{
    int length;
    int index;
}Node;

int main()
{
    // 初始化输入
    int num;
    if(num<3)
    {
         cout << -1 << " " << -1 << endl;
         return 0;
     }
    vector<int>vecin;
    vecin.resize(num);
    for(int i=0; i<num; ++i)
    {
        cin >> vecin[i];  
    }
    map<int, int>m;
    int left = -1, right = -1;
    // 从左到右数区间上升
    int index= 0, length = 1;
    for(int i=1; i<num; ++i)
    {
        if(vecin[i]<=vecin[i-1])
        {
            if(length>1)
                     {
                            m[index] = length;
                     }                      left = i;
                    length = 1;  }
        else
        {
            ++index;
            ++length;
        }
    }
    // 从右向左数区间下降
    int max = -1;
    for(int i=num-2; i>=0; ++i)
    {
        if(vecin[i]<=vecin[i+1])
        {
            if(length>1)
                     {
                            if(!m[index] )
                            {
                                    index = i;
                                    length = 1;
                                    continue;
                            }
                            else
                            {
                                    if(length+m[index] > max)
                                    {
                                            left = index - m[index] + 1;
                                            right = index - length - 1;  }  }  } 
                     left = i;
                    length = 1;  }
        else
        {
            --index;
            ++length;
        }
}



cout << left << " " << right << endl;

return 0;

}

}

#include <iostream>
#include <vector>
using namespace std;
int n;
int main(){
	while(cin >> n){
		vector<int> nums(n);
		for(int i = 0; i < n; i++) cin >> nums[i];
		int left = -1, right = -1, tmp_left = -1, tmp_right = -1, res = 0;
		for(int i = 1; i < n; ){
			tmp_left = i;
			while( i < n && nums[i] > nums[i-1]) i++;
			if(i == n) break;
			if(i == tmp_left){i++; continue;}
			i++;
			while(i < n && nums[i] < nums[i-1]) i++;
			cout << tmp_left << " " << i << endl;
			if(i - tmp_left + 1 > res){
				left = tmp_left - 1;
				right = i -1;
				res = i - tmp_left + 1;
			}
		}
		cout << left << " " << right << endl;
	}
	return 0;
}

#include <iostream> #include <string> #include <vector> #include <algorithm>  using namespace std; int main(){ int n; while(cin>>n){ vector<int> v; for(int i=0;i<n;i++){ int a;
            cin>>a;
            v.push_back(a);
        } bool flag = false; int cur=0;int max=0; int left=0,right=0; for(int i=1;i<n-1;i++){ if(flag){ if(v[i]<v[i-1]&&v[i+1]>v[i]){ if((i-cur)>max){
                        max=i-cur;
                        left=cur;
                        right=i;
                    }
                    cur=i;
                }
            }else{ if(v[i]>v[i-1]){
                    flag=true;
                    cur=i-1;
                }
            }
        } if(v[n-1]<v[n-2]){ if((n-1-cur)>max){
                left=cur;
                right=n-1;
            }
        }
        cout<<left<<" "<<right<<endl;
    } return 0;
}

import java.util.ArrayList; import java.util.Scanner;  public class Main {   public static void main(String[] args) {  // write your code here  Scanner in = new Scanner(System.in);  int n = in.nextInt();  int[] arr = new int[n];  for (int i=0; i<n; i++){  arr[i] = in.nextInt();  }  int flag = 0;  int[] result = new int[2];  if (n==1){  result[0] = -1;  result[1] = -1;  }  for (int i=0; i<n-1; i++){  if (arr[i+1]-arr[i]>0)  flag++;  }  if (flag==0 || flag==n-1){  result[0] = -1;  result[1] = -1;  }else {  ArrayList<Integer> list = new ArrayList<Integer>();  if (arr[0]<arr[1]){  list.add(0);  }  for (int i=1; i<n-1; i++){  if (arr[i-1]>arr[i] && arr[i+1]>arr[i])  list.add(i);  }  int max=0;  for (int i=0; i<list.size()-1; i++){  if ((list.get(i+1)-list.get(i))>max){  max = list.get(i+1)-list.get(i);  result[0] = list.get(i);  result[1] = list.get(i+1);  }   }  }    System.out.println(result[0] + " " + result[1]);  } }