[BZOJ 1058] [ZJOI2007] 报表统计 【平衡树】

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <map>
#include <set>

using namespace std;

const int MaxN = 500000 + 5, INF = 1000000015, MaxL = 25;

int n, m, MSG;
int A[MaxN], B[MaxN];

char Str[MaxL];

 
multiset<int> S, S2;
multiset<int>::iterator It, It2;

inline int gmax(int a, int b) {return a > b ? a : b;}
inline int gmin(int a, int b) {return a < b ? a : b;}
inline int Abs(int a) {return a < 0 ? -a : a;}

void Before(int x) 
{
	It = S.lower_bound(x);
	if (It == S.end()) 
	{
		It--;
		MSG = gmin(MSG, x - *It);
		return;
	}
	if (*It == x) 
	{
		MSG = 0;
		return;
	}
	if (It == S.begin()) return;
	It--;
	MSG = gmin(MSG, x - *It);
}

void After(int x) 
{
	It = S.upper_bound(x);
	if (It == S.end()) return;
	MSG = gmin(MSG, *It - x);
}

int main()
{
	scanf("%d%d", &n, &m);
	S.clear(); S2.clear();
	for (int i = 1; i <= n; ++i) 
	{
		scanf("%d", &A[i]);
		B[i] = A[i];
		S.insert(A[i]);
	}
	for (int i = 2; i <= n; ++i) 
		S2.insert(Abs(A[i] - A[i - 1]));
	MSG = INF;
	for (int i = 1; i <= n; ++i) 
	{
		S.erase(S.find(A[i]));
		Before(A[i]);
		After(A[i]);
		S.insert(A[i]);
	}
	int Pos, Num;
	for (int i = 1; i <= m; ++i) 
	{
		scanf("%s", Str + 1);
		if (Str[1] == ‘I‘) 
		{
			scanf("%d%d", &Pos, &Num);
			Before(Num);
			After(Num);
			S.insert(Num);
			if (Pos == n) 
			{
				B[Pos] = Num;
				continue;
			}
			S2.erase(S2.find(Abs(A[Pos + 1] - B[Pos])));
			S2.insert(Abs(Num - B[Pos]));
			S2.insert(Abs(A[Pos + 1] - Num));
			B[Pos] = Num;
		}
		else if (Str[5] == ‘G‘) 
		{
			It2 = S2.begin();
			printf("%d\n", *It2);
		}
		else 
		{
			printf("%d\n", MSG);
		}
	}
	return 0;
}