codeforces 361D rmq st算法模板_codeforces上的st模板题-优快云博客

本文介绍了一种使用区间动态规划优化算法解决特定问题的方法。通过预处理最大值和最小值，能够在给定区间内快速查询最优解，适用于需要频繁查询区间最大最小值的应用场景。

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类似区间DP

#include<algorithm>
#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstdio>
#include<stack>
#include<cmath>
#include<cstring>
#define LL long long
#include<string>
#include<cmath>
#include<queue>
#define lson i<<1
#define rson (i<<1)+1
using namespace std;

int a[200005],b[200005],stA[200005][25],stB[200005][25],n;

void solve()
{
     for(int i=1;i<=n;i++)stA[i][0] = a[i];
     for(int i=1;i<=n;i++)stB[i][0] = b[i];

     for(int i=1;i<=(int)(log(n)/log(2));i++)
        for(int j=1;j+(1<<i)-1<=n;j++)
        {
            stA[j][i] = max(stA[j][i-1],stA[j+(1<<(i-1))][i-1]);
            stB[j][i] = min(stB[j][i-1],stB[j+(1<<(i-1))][i-1]);
        }
}

int queryA(int l,int r)
{
    int pre = (int)(log(r-l+1)/log(2));
    return max(stA[l][pre],stA[r-(1<<pre)+1][pre]);
}

int queryB(int l,int r)
{
    int pre = (int)(log(r-l+1)/log(2));
    return min(stB[l][pre],stB[r-(1<<pre)+1][pre]);
}

int main()
{
    scanf("%d",&n);

    LL sum = 0;

    for(int i=1;i<=n;i++)scanf("%d",&a[i]);
    for(int i=1;i<=n;i++)scanf("%d",&b[i]);
    solve();

    for(int i=1;i<=n;i++)
    {
        int l = i,r = n;
        int ansl = 0;
        while(l<=r)
        {
            int mid = (l+r)/2,vaA = queryA(i,mid),vaB = queryB(i,mid);
            if(vaA<vaB)l = mid+1;
            else if(vaA==vaB){ansl = mid;r = mid-1;}
            else r = mid-1;
        }
        l = i,r = n;
        int ansr = -1;
        while(l<=r)
        {
            int mid = (l+r)/2,vaA = queryA(i,mid),vaB = queryB(i,mid);
            if(vaA<vaB)l = mid+1;
            else if(vaA==vaB){ansr = mid;l = mid+1;}
            else r = mid-1;
        }
        sum+=ansr-ansl+1ll;
    }

    printf("%I64d\n",sum);
    return 0;
}