Codeforces Round #333 (Div. 1)--B. Lipshitz Sequence 单调栈

 1 import java.io.BufferedInputStream;
 2 import java.io.BufferedOutputStream;
 3 import java.io.PrintWriter;
 4 import java.util.Scanner;
 5 
 6 
 7 
 8 public class Main {
 9     static Scanner cin = new Scanner(new BufferedInputStream(System.in));
10     static PrintWriter cout = new PrintWriter(new BufferedOutputStream(System.out));
11     static final int maxn = 100005;
12     public static void main(String[] args) {
13         int []height = new int[maxn];
14         while (cin.hasNext()){
15             int n = cin.nextInt();
16             int q = cin.nextInt();
17             height[0] = 0;
18             for (int i = 1; i <= n; i++){
19                 height[i] = cin.nextInt();
20                 height[i-1] = Math.abs(height[i]-height[i-1]); 
21             }
22             int []stack = new int[maxn];
23             int top = -1;
24             for (int i = 0; i < q; i++){
25                 int l = cin.nextInt();
26                 int r = cin.nextInt();
27                 long res = 0, cur = 0;
28                 top = -1;
29                 for (int j = l; j < r; j++){
30                     while (top >= 0 && height[stack[top]] <= height[j]){
31                         cur -= 1L * height[stack[top]] * (stack[top] - (top==0 ? l-1 : stack[top-1]));
32                         top--;
33                     }
34                     if (top >= 0){
35                         cur += 1L* (j - stack[top]) * height[j]; 
36                     }else{
37                         cur += 1L * (j - l + 1) * height[j];
38                     }
39                     stack[++top] = j;
40                     res += cur;
41                 }
42                 
43                 cout.println(res);                
44             }
45             cout.flush();
46         }
47     }
48 
49 }