【SPOJ】4487 Can you answer these queries VI

仍然是询问区间最大连续和，只不过多了插入和删除操作。

线段树搞不定了。。伸展树来了。

插入删除偷懒那样写了，加了读入优化卡过的。

#include<cstdio>
#include<iostream>
#define MAX(a,b) ((a)>(b)?(a):(b))
#define oo 1000000000
#define MAXN 200010
using namespace std;
int n, a[MAXN];
struct SplayTree {
    int root, size;
    int next[MAXN][2], pre[MAXN];
    int num[MAXN], key[MAXN];
    int left[MAXN], right[MAXN], sum[MAXN], val[MAXN];
    void NewNode(int &x, int father, int nb) {
        x = ++size;
        next[x][0] = next[x][1] = 0;
        pre[x] = father;
        num[x] = 1;
        key[x] = left[x] = right[x] = sum[x] = val[x] = nb;
    }
    inline void PushUp(int x) {
        int L, R;
        L = next[x][0], R = next[x][1];
        num[x] = num[L] + num[R] + 1;
        sum[x] = sum[L] + sum[R] + key[x];
        left[x] = MAX(left[L],sum[L]+key[x]+MAX(left[R],0));
        right[x] = MAX(right[R],sum[R]+key[x]+MAX(right[L],0));
        val[x] = MAX(val[L],val[R]);
        val[x] = MAX(val[x],key[x]+MAX(right[L],0)+MAX(left[R],0));
    }
    void Build(int L, int R, int &x, int father) {
        if (L <= R) {
            int mid = (L + R) >> 1;
            NewNode(x, father, a[mid]);
            Build(L, mid - 1, next[x][0], x);
            Build(mid + 1, R, next[x][1], x);
            PushUp(x);
        }
    }
    void Init() {
        size = root = 0;
        next[0][0] = next[0][1] = 0;
        pre[0] = 0;
        sum[0] = num[0] = 0;
        key[0] = left[0] = right[0] = val[0] = -oo;
        NewNode(root, 0, -oo);
        NewNode(next[root][1], root, -oo);
        Build(1, n, next[next[root][1]][0], next[root][1]);
        PushUp(next[root][1]);
        PushUp(root);
    }
    void Rotate(int x, int kind) {
        int y, z;
        y = pre[x];
        z = pre[y];
        next[y][!kind] = next[x][kind];
        pre[next[x][kind]] = y;
        next[z][next[z][1] == y] = x;
        pre[x] = z;
        next[x][kind] = y;
        pre[y] = x;
        PushUp(y);
    }
    void Splay(int x, int goal) {
        if (x != goal) {
            while (pre[x] != goal) {
                if (next[pre[x]][0] == x)
                    Rotate(x, 1);
                else
                    Rotate(x, 0);
            }
            PushUp(x);
            if (!goal)
                root = x;
        }
    }
    int Select(int k) {
        int x;
        for (x = root; num[next[x][0]] + 1 != k;) {
            if (k <= num[next[x][0]])
                x = next[x][0];
            else {
                k -= num[next[x][0]] + 1;
                x = next[x][1];
            }
        }
        return x;
    }
    void Insert(int k, int val) {
        int a, b;
        a = Select(k);
        b = Select(k + 1);
        Splay(a, 0);
        Splay(b, a);
        NewNode(next[b][0], b, val);
        PushUp(b);
        PushUp(a);
    }
    void Delete(int k) {
        int a, b;
        a = Select(k);
        b = Select(k + 2);
        Splay(a, 0);
        Splay(b, a);
        next[b][0] = 0;
        PushUp(b);
        PushUp(a);
    }
    void Update(int k, int val) {
        int a;
        a = Select(k + 1);
        key[a] = val;
        Splay(a, 0);
    }
    int Query(int x, int y) {
        x = Select(x);
        y = Select(y + 2);
        Splay(x, 0);
        Splay(y, x);
        return val[next[y][0]];
    }
} spt;
int INT() {
    int res;
    char ch;
    bool neg;
    while (ch = getchar(), !isdigit(ch) && ch != '-')
        ;
    if (ch == '-') {
        res = 0;
        neg = true;
    } else {
        res = ch - '0';
        neg = false;
    }
    while (ch = getchar(), isdigit(ch))
        res = res * 10 + ch - '0';
    return neg ? -res : res;
}
char CHAR() {
    char res;
    while (res = getchar(), !isalpha(res))
        ;
    return res;
}
int main() {
    char ch;
    int i, q, x, y;
    while (~scanf("%d", &n)) {
        for (i = 1; i <= n; i++)
            a[i] = INT();
        spt.Init();
        q = INT();
        while (q--) {
            ch = CHAR(), x = INT();
            if (ch != 'D')
                y = INT();
            if (ch == 'I')
                spt.Insert(x, y);
            else if (ch == 'D')
                spt.Delete(x);
            else if (ch == 'R')
                spt.Update(x, y);
            else
                printf("%d\n", spt.Query(x, y));
        }
    }
    return 0;
}