支持操作：
1.区间加
2.区间翻转
3.区间求最大值
splay模板
注意：update 里更新 max 时需要取 3 个值的 Max
别忘了各种边界讨论
——代码
1 #include <cstdio> 2 #define ls son[now][0] 3 #define rs son[now][1] 4 5 const int MAXN = 50010, INF = 2e9; 6 int n, m, root, cnt; 7 int a[MAXN], size[MAXN], key[MAXN], add[MAXN], max[MAXN], rev[MAXN], f[MAXN], son[MAXN][2]; 8 9 inline void swap(int &x, int &y) 10 { 11 x ^= y ^= x ^= y; 12 } 13 14 inline int Max(int x, int y) 15 { 16 return x > y ? x : y; 17 } 18 19 inline int get(int x) 20 { 21 return x == son[f[x]][1]; 22 } 23 24 inline void update(int now) 25 { 26 if(now) 27 { 28 size[now] = 1; 29 if(ls) size[now] += size[ls]; 30 if(rs) size[now] += size[rs]; 31 32 max[now] = key[now]; 33 if(ls) max[now] = Max(max[now], max[ls]); 34 if(rs) max[now] = Max(max[now], max[rs]); 35 } 36 } 37 38 inline void pushdown(int now) 39 { 40 if(rev[now]) 41 { 42 swap(ls, rs); 43 if(ls) rev[ls] ^= 1; 44 if(rs) rev[rs] ^= 1; 45 rev[now] = 0; 46 } 47 if(add[now]) 48 { 49 if(ls) add[ls] += add[now], key[ls] += add[now], max[ls] += add[now]; 50 if(rs) add[rs] += add[now], key[rs] += add[now], max[rs] += add[now]; 51 add[now] = 0; 52 } 53 } 54 55 inline void build(int x, int y, int fa, int &now) 56 { 57 if(x > y) return; 58 int mid = (x + y) >> 1; 59 now = ++cnt; 60 f[now] = fa; 61 build(x, mid - 1, now, ls); 62 build(mid + 1, y, now, rs); 63 update(now); 64 } 65 66 inline void rotate(int x) 67 { 68 pushdown(f[x]); 69 pushdown(x); 70 int old = f[x], oldf = f[old], wh = get(x); 71 72 son[old][wh] = son[x][wh ^ 1]; 73 f[son[old][wh]] = old; 74 75 if(oldf) son[oldf][old == son[oldf][1]] = x; 76 f[x] = oldf; 77 78 son[x][wh ^ 1] = old; 79 f[old] = x; 80 81 update(old); 82 update(x); 83 } 84 85 inline void splay(int x, int to) 86 { 87 for(int fa; (fa = f[x]) != to; rotate(x)) 88 if(f[fa] != to) 89 rotate(get(x) ^ get(fa) ? x : fa); 90 if(!to) root = x; 91 } 92 93 inline int find(int x) 94 { 95 int now = root; 96 while(1) 97 { 98 pushdown(now); 99 if(x <= size[ls]) now = ls; 100 else 101 { 102 x -= size[ls]; 103 if(x == 1) return now; 104 x--; 105 now = rs; 106 } 107 } 108 } 109 110 int main() 111 { 112 int i, k, x, y, v; 113 scanf("%d %d", &n, &m); 114 a[1] = -INF, a[n + 2] = -INF; 115 build(1, n + 2, 0, root); 116 for(i = 1; i <= m; i++) 117 { 118 scanf("%d %d %d", &k, &x, &y); 119 x = find(x); 120 y = find(y + 2); 121 splay(x, 0); 122 splay(y, x); 123 if(k == 1) 124 { 125 scanf("%d", &v); 126 add[son[son[root][1]][0]] += v; 127 max[son[son[root][1]][0]] += v; 128 key[son[son[root][1]][0]] += v; 129 update(son[root][1]); 130 update(root); 131 } 132 else if(k == 2) rev[son[son[root][1]][0]] ^= 1; 133 else printf("%d ", max[son[son[root][1]][0]]); 134 } 135 return 0; 136 }