复杂度: O(nlogn)
#include<stdio.h>
#include<iostream>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<set>
#include<iterator>
#include<map>
using namespace std;
typedef unsigned long long ll;
int main()
{
int t, n;
ll m;
scanf("%d", &t);
ll maxm = 0;
while(t--){
scanf("%d", &n);
pair<ll, int> a[n];
scanf("%llu", &m);
for(int i = 0; i < n; i++){
scanf("%llu", &a[i].first);
a[i].second = i + 1;
}
a[0].first = a[0].first % m;
ll maxm = a[0].first;
for(int i = 1; i < n; i++){
a[i].first = (a[i].first%m + a[i-1].first%m) % m;
if(maxm < a[i].first) maxm = a[i].first;
}
sort(a, a + n);
ll minm = 1e15;
for(int i = 0; i < n - 1; i++){
if(a[i].second > a[i + 1].second){
if(minm > a[i+1].first - a[i].first){
minm = a[i+1].first - a[i].first;
}
}
}
printf("%llu\n", max(maxm, m-minm));
}
return 0;
}