40 lines
1.2 KiB
Java
40 lines
1.2 KiB
Java
import java.util.*;
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public class non {
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static void min(long[] a, int[] b, int start, int end, int step, int root){
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Stack<Integer> st = new Stack<>();
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for(int i=start;i!=end;i+=step){
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while(!st.isEmpty() && a[st.lastElement()] >= a[i]) st.pop();
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if(st.isEmpty()) b[i] = root;
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else b[i] = st.lastElement();
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st.push(i);
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}
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}
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public static void main(String[] args) {
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Scanner sc = new Scanner(System.in);
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int T = 2;
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int m = sc.nextInt(), n = sc.nextInt();
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long[] arr = new long[n];
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long res = 0;
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for(int i=0;i<n;i++) arr[i] = sc.nextLong();
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while(T-->0){
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long[] a = new long[n];
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for(int i=0;i<n;i++){
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if(T==1) a[i]=arr[i];
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else a[i]=m-arr[i];
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}
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int[] l = new int[n];
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int[] r = new int[n];
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min(a, l, 0, n, 1, -1);
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min(a, r, n-1, -1, -1, n);
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long ans = 0;
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for(int i=0;i<n;i++){
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ans = Math.max(ans, a[i]*(r[i]-l[i]-1));
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}
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res = Math.max(res, ans);
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}
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System.out.println(res);
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}
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}
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