CF279C Ladder 简单DP

L[x]代表不递增序列，从x位置向左最远能延伸到的位置

R[x]代表不递减序列，从x位置向右最远能延伸到的位置

给出x，y

只用判断R[x]是否>=L[y]即可。

一看就感觉是水题。

C. Ladder

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

You've got an array, consisting of n integers a1, a2, ..., an. Also, you've got m queries, the i-th query is described by two integers li, ri. Numbersli, ri define a subsegment of the original array, that is, the sequence of numbers ali, ali + 1, ali + 2, ..., ari. For each query you should check whether the corresponding segment is a ladder.

A ladder is a sequence of integers b1, b2, ..., bk, such that it first doesn't decrease, then doesn't increase. In other words, there is such integer x(1 ≤ x ≤ k), that the following inequation fulfills: b1 ≤ b2 ≤ ... ≤ bx ≥ bx + 1 ≥ bx + 2... ≥ bk. Note that the non-decreasing and the non-increasing sequences are also considered ladders.

Input

The first line contains two integers n and m (1 ≤ n, m ≤ 105) — the number of array elements and the number of queries. The second line contains the sequence of integers a1, a2, ..., an (1 ≤ ai ≤ 109), where number ai stands for the i-th array element.

The following m lines contain the description of the queries. The i-th line contains the description of the i-th query, consisting of two integers li, ri(1 ≤ li ≤ ri ≤ n) — the boundaries of the subsegment of the initial array.

The numbers in the lines are separated by single spaces.

Output

Print m lines, in the i-th line print word "Yes" (without the quotes), if the subsegment that corresponds to the i-th query is the ladder, or word "No" (without the quotes) otherwise.

Examples

input

8 61 2 1 3 3 5 2 11 32 32 48 81 45 8

output

YesYesNoYesNoYes

#include<cstdio>#include<string>#include<cstring>#include<iostream>#include<cmath>#include<algorithm>using namespace std;typedef long long ll;const int INF =0x3f3f3f3f;const int maxn= 100000   ;int a[maxn+5];int R[maxn+5];int L[maxn+5];int n,m;int main(){    while(~scanf("%d%d",&n,&m))    {        for(int i=1;i<=n;i++)        {            scanf("%d",&a[i]);        }        R[n]=n;        for(int i=n-1;i>=1;i--)        {            if(a[i+1]<a[i])  R[i]=i;            else            {                R[i]=R[i+1];            }        }        L[1]=1;        for(int i=2;i<=n;i++)        {            if(a[i-1]<a[i]) L[i]=i;            else            {                L[i]=L[i-1];            }        }        int le,ri;        for(int i=1;i<=m;i++)        {            scanf("%d%d",&le,&ri);            puts(R[le]>=L[ri]?"Yes":"No");        }    }   return 0;}