UVA 1442 Cav

#include<bits/stdc++.h>
#define REP(i,a,b) for(int i=a;i<=b;i++)
#define MS0(a) memset(a,0,sizeof(a))

using namespace std;

typedef long long ll;
const int maxn=1000100;
const int INF=1<<29;

int n;
int p[maxn],s[maxn];
int L[maxn],R[maxn],d[maxn];

void solve()
{
    L[1]=s[1];
    REP(i,2,n){
        L[i]=max(L[i-1],p[i]);
        L[i]=min(L[i],s[i]);
    }
    R[n]=s[n];
    for(int i=n-1;i>=1;i--){
        R[i]=max(R[i+1],p[i]);
        R[i]=min(R[i],s[i]);
    }
    REP(i,1,n) d[i]=min(L[i],R[i]);
    int ans=0;
    REP(i,1,n) ans+=d[i]-p[i];
    cout<<ans<<endl;
    /*
    REP(i,1,n) printf("%2d ",i);cout<<endl;
    REP(i,1,n) printf("%2d ",p[i]);cout<<endl;
    REP(i,1,n) printf("%2d ",s[i]);cout<<endl;
    REP(i,1,n) printf("%2d ",L[i]);cout<<endl;
    REP(i,1,n) printf("%2d ",R[i]);cout<<endl;
    */
}

int main()
{
    freopen("in.txt","r",stdin);
    int T;cin>>T;
    while(T--){
        scanf("%d",&n);
        REP(i,1,n) scanf("%d",&p[i]);
        REP(i,1,n) scanf("%d",&s[i]);
        solve();
    }
    return 0;
}
/**
虽然看起来很难实现，但是画个图很容易理解。
codeforces上也看过一次这种题，第一眼竟然没有看出解法...why am i so stupid...
*/