題目鏈接：http://acm.hdu.edu.cn/showproblem.php?pid=3397 這道題是一個我認為非常非常麻煩的題，操作非常多，而且要打兩個懶惰標記，并且懶惰標記有優先級之分，當一個節點收到一個覆蓋標記的時候，取反標記就應該立即消失，這是一個麻煩，另外一個麻煩就是一個結點需要維持七個變量以滿足本題的操作和所求。區間合并 的基本思想不用贅述，下面有一個成形的代碼（貌似有bug），不過想法已經體現出來。
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1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 using namespace std;
5 #define lson l, m, rt<<1
6 #define rson m + 1, r, rt<<1|1
7 const int maxn = 111111;
8 int l1s[maxn<<2], r1s[maxn<<2], m1s[maxn<<2], l0s[maxn<<2], r0s[maxn<<2], m0s[maxn<<2], sum[maxn<<2];
9 int cover[maxn<<2], col[maxn<<2];
10 void PushDown(int rt, int m){
11 if (cover[rt] != -1){
12 cover[rt<<1] = cover[rt<<1|1] = cover[rt];
13 col[rt] = col[rt<<1] = col[rt<<1|1] = 0;
14 l1s[rt<<1] = r1s[rt<<1] = m1s[rt<<1] = sum[rt<<1] = cover[rt] ? m - (m >> 1) : 0;
15 l1s[rt<<1|1] = r1s[rt<<1|1] = m1s[rt<<1|1] = sum[rt<<1|1] = cover[rt] ? (m >> 1) : 0;
16 l0s[rt<<1] = r0s[rt<<1] = m0s[rt<<1] = cover[rt] ? 0 : m - (m >> 1);
17 l0s[rt<<1|1] = r0s[rt<<1|1] = m0s[rt<<1|1] = cover[rt] ? 0 : (m >> 1);
18 cover[rt] = -1;
19 }
20 else if (col[rt]){
21 col[rt<<1] += col[rt];
22 col[rt<<1|1] += col[rt];
23 col[rt] %= 2;
24 if (col[rt]){
25 swap(l1s[rt<<1], l0s[rt<<1]);
26 swap(l1s[rt<<1|1], l0s[rt<<1|1]);
27 swap(r1s[rt<<1], r0s[rt<<1]);
28 swap(r1s[rt<<1|1], r0s[rt<<1|1]);
29 swap(m1s[rt<<1], m0s[rt<<1]);
30 swap(m1s[rt<<1|1], m0s[rt<<1|1]);
31 sum[rt<<1] = (m - (m>>1)) - sum[rt<<1];
32 sum[rt<<1|1] = (m>>1) - sum[rt>>1|1];
33 }
34 col[rt] = 0;
35 }
36 }
37 void PushUp(int rt, int m){
38 l1s[rt] = l1s[rt<<1]; l0s[rt] = l0s[rt<<1];
39 r1s[rt] = r1s[rt<<1|1]; r0s[rt] = r0s[rt<<1|1];
40 if (l1s[rt] == m - (m >> 1)) l1s[rt] += l1s[rt<<1|1];
41 if (r1s[rt] == (m >> 1)) r1s[rt] += r1s[rt<<1];
42 if (l0s[rt] == m - (m >> 1)) l0s[rt] += l0s[rt<<1|1];
43 if (r0s[rt] == (m >> 1)) r0s[rt] += r0s[rt<<1];
44 m1s[rt] = max(l1s[rt<<1|1] + r1s[rt<<1], max(m1s[rt<<1], m1s[rt<<1|1]));
45 m0s[rt] = max(l0s[rt<<1|1] + r0s[rt<<1], max(m0s[rt<<1], m0s[rt<<1|1]));
46 sum[rt] = sum[rt<<1] + sum[rt<<1|1];
47 }
48 void build(int l, int r, int rt){
49 cover[rt] = -1; col[rt] = 0;
50 if (l == r){
51 scanf("%d", &sum[rt]);
52 l1s[rt] = r1s[rt] = m1s[rt] = cover[rt] = sum[rt];
53 l0s[rt] = r0s[rt] = m0s[rt] = 1 - sum[rt];
54 return;
55 }
56 int m = (l + r) >> 1;
57 build(lson);
58 build(rson);
59 PushUp(rt, r - l + 1);
60 }
61 void update(int ll, int rr, int c, int l, int r, int rt){
62 if (ll <= l && rr >= r){
63 if (c == 2){
64 col[rt] += 1;
65 sum[rt] = (r - l + 1) - sum[rt];
66 swap(m1s[rt], m0s[rt]);
67 swap(l1s[rt], l0s[rt]);
68 swap(r1s[rt], r0s[rt]);
69 }
70 else{
71 l1s[rt] = r1s[rt] = m1s[rt] = sum[rt] = c ? (r - l + 1) : 0;
72 l0s[rt] = r0s[rt] = m0s[rt] = c ? 0 : r - l + 1;
73 col[rt] = 0;
74 cover[rt] = c;
75 }
76 }
77 PushDown(rt, r - l + 1);
78 int m = (l + r) >> 1;
79 if (ll <= m) update(ll, rr, c, lson);
80 if (rr > m) update(ll, rr, c, rson);
81 PushUp(rt, r - l + 1);
82 }
83 int query_sum(int ll, int rr, int l, int r, int rt){
84 if (ll <= l && rr >= r) return sum[rt];
85 PushDown(rt, r - l + 1);
86 int m = (l + r) >> 1;
87 int ret = 0;
88 if (ll <= m) ret += query_sum(ll, rr, lson);
89 if (rr > m) ret += query_sum(ll, rr, rson);
90 return ret;
91 }
92 int query_maxlen(int ll, int rr, int l, int r, int rt){
93 if (ll == l && rr == r) return m1s[rt];
94 PushDown(rt, r - l + 1);
95 int m = (l + 1) >> 1;
96 if (rr <= m) return query_maxlen(ll, rr, lson);
97 else if (ll >= m) return query_maxlen(ll, rr, rson);
98 else{
99 int a = query_maxlen(ll, m, lson);
100 int b = query_maxlen(m+1, rr, rson);
101 int c = 0;
102 c += max(r1s[rt<<1], m - ll + 1);
103 c += max(l1s[rt<<1|1], rr - m);
104 return max(a, max(b, c));
105 }
106 }
107 int main(){
108 int t;
109 scanf("%d", &t);
110 while(t--){
111 int op, a, b;
112 int n, m;
113 scanf("%d%d", &n, &m);
114 build(1, n, 1);
115 while(m--){
116 scanf("%d%d%d", &op, &a, &b);
117 a += 1; b += 1;
118 if (op <= 2)
119 update(a, b, op, 1, n, 1);
120 else if (op == 3){
121 int ans = query_sum(a, b, 1, n, 1);
122 printf("%d\n", ans);
123 }
124 else{
125 int ans = query_maxlen(a, b, 1, n, 1);
126 printf("%d\n", ans);
127 }
128 }
129 }
130 return 0;
131
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