Can you answer these queries VII 【SPOJ - GSS7】【树链剖分 最大子段和】

题目链接

  造了好多组样例，最后的时候发现，竟然是update的时候区间的更新并没有完全更新到位，导致最后变成WA了，竟然是WA了后面的几组，还让我一度以为是找区间的时候出现了问题。

  然后剩下的就是一些简单的线段树了，最难处理的不过是在树上公公祖先的那部分，debug200+行的代码真的挺难的，尤其是今早的时候灵光闪现！

[code]#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f
#define efs 1e-6
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
#define max3(a, b, c) max(a, max(b, c))
#define max4(a, b, c, d) max(max(a, b), max(c, d))
#define max5(a, b, c, d, f) max4(a, b, c, max(d, f))
#define max6(a, b, c, d, f, g) max(max3(a, b, c), max3(d, f, g))
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 1e5 + 7;
int N, Q, head[maxN], cnt, a[maxN], tot;
struct Eddge
{
int nex, to;
Eddge(int a=-1, int b=0):nex(a), to(b) {}
}edge[maxN<<1];
inline void addEddge(int u, int v)
{
edge[cnt] = Eddge(head[u], v);
head[u] = cnt++;
}
inline void _add(int u, int v) { addEddge(u, v); addEddge(v, u); }
int root[maxN], deep[maxN], siz[maxN], W_son[maxN];
void dfs1(int u, int fa, int depth)
{
root[u] = fa;
deep[u] = depth;
siz[u] = 1;
W_son[u] = -1;
int maxx = 0;
for(int i=head[u], v; ~i; i=edge[i].nex)
{
v = edge[i].to;
if(v == fa) continue;
dfs1(v, u, depth + 1);
siz[u] += siz[v];
if(siz[v] > maxx)
{
maxx = siz[v];
W_son[u] = v;
}
}
}
int top[maxN], id[maxN], w[maxN];
void dfs2(int u, int topf)
{
top[u] = topf;
id[u] = ++tot;
w[tot] = a[u];
if(W_son[u] == -1) return;
dfs2(W_son[u], topf);
for(int i=head[u], v; ~i; i=edge[i].nex)
{
v = edge[i].to;
if(v == root[u] || v == W_son[u]) continue;
dfs2(v, v);
}
}
struct node
{
int lm, rm, mx, all, lazy;
bool op;
node()
{
lm = rm = mx = all = lazy = 0;
op = false;
}
void give(int x) { lm = rm = mx = all = x; }
}tree[maxN<<2];
inline void pushdown(int rt, int l, int r)
{
if(tree[rt].op)
{
int mid = HalF;
tree[lsn].mx = tree[lsn].rm = tree[lsn].lm = (tree[rt].lazy > 0 ? tree[rt].lazy * (mid - l + 1) : tree[rt].lazy);
tree[rsn].mx = tree[rsn].rm = tree[rsn].lm = (tree[rt].lazy > 0 ? tree[rt].lazy * (r - mid) : tree[rt].lazy);
tree[lsn].all = tree[rt].lazy * (mid - l + 1);
tree[rsn].all = tree[rt].lazy * (r - mid);
tree[lsn].lazy = tree[rsn].lazy = tree[rt].lazy;
tree[rt].lazy = 0;
tree[rt].op = false;
tree[lsn].op = tree[rsn].op = true;
}
}
inline void pushup(node &rt, node lc, node rc)
{
rt.lm = max(lc.lm, lc.all + rc.lm);
rt.rm = max(rc.rm, rc.all + lc.rm);
rt.all = lc.all + rc.all;
rt.mx = max3(lc.mx, rc.mx, lc.rm + rc.lm);
}
void buildTree(int rt, int l, int r)
{
if(l == r)
{
tree[rt].give(w[l]);
return;
}
int mid = HalF;
buildTree(Lson); buildTree(Rson);
pushup(tree[rt], tree[lsn], tree[rsn]);
}
void update(int rt, int l, int r, int ql, int qr, int val)
{
if(ql <= l && qr >= r)
{
tree[rt].lm = tree[rt].rm = tree[rt].mx = ( val > 0 ? val * (r - l + 1) : val );
tree[rt].op = true;
tree[rt].lazy = val;
tree[rt].all = val * (r - l + 1);
return;
}
pushdown(myself);
int mid = HalF;
if(qr <= mid) update(QL, val);
else if(ql > mid) update(QR, val);
else
{
update(QL, val);
update(QR, val);
}
pushup(tree[rt], tree[lsn], tree[rsn]);
}
node query(int rt, int l, int r, int ql, int qr)
{
if(ql <= l && qr >= r) return tree[rt];
pushdown(myself);
int mid = HalF;
if(qr <= mid) return query(QL);
else if(ql > mid) return query(QR);
else
{
node TL = query(QL), TR = query(QR), ans;
pushup(ans, TL, TR);
return ans;
}
}
inline int query_range(int x, int y)
{
node TX, TY, tmp;
while(top[x] != top[y])
{
if(deep[top[x]] > deep[top[y]]) //走x
{
tmp = query(1, 1, N, id[top[x]], id[x]);
pushup(TX, query(1, 1, N, id[top[x]], id[x]), TX);
x = root[top[x]];
}
else    //走y
{
pushup(TY, query(1, 1, N, id[top[y]], id[y]), TY);
y = root[top[y]];
}
}
if(deep[x] > deep[y])
{
pushup(TX, query(1, 1, N, id[y], id[x]), TX);
}
else
{
pushup(TY, query(1, 1, N, id[x], id[y]), TY);
}
return max4(0, TY.mx, TX.mx, TX.lm + TY.lm);
}
inline void updata_range(int x, int y, int w)
{
while(top[x] != top[y])
{
if(deep[top[x]] < deep[top[y]]) swap(x, y);
update(1, 1, N, id[top[x]], id[x], w);
x = root[top[x]];
}
if(deep[x] < deep[y]) swap(x, y);
update(1, 1, N, id[y], id[x], w);
}
inline void init()
{
cnt = tot = 0;
for(int i=1; i<=N; i++) head[i] = -1;
}
int main()
{
scanf("%d", &N);
init();
for(int i=1; i<=N; i++) scanf("%d", &a[i]);
for(int i=1, u, v; i<N; i++)
{
scanf("%d%d", &u, &v);
_add(u, v);
}
dfs1(1, 1, 0);
dfs2(1, 1);
buildTree(1, 1, N);
scanf("%d", &Q);
int ch, a, b, c;
while(Q--)
{
scanf("%d%d%d", &ch, &a, &b);
if(ch == 1) printf("%d\n", query_range(a, b));
else
{
scanf("%d", &c);
updata_range(a, b, c);
}
}
return 0;
}
/*
8
0 -2 3 -1 1 5 -10 2
1 2
1 3
2 4
2 5
3 6
6 7
6 8
*/