|
74 | 74 |
|
75 | 75 | <!-- 这里可写通用的实现逻辑 -->
|
76 | 76 |
|
77 |
| -树状数组。 |
| 77 | +**方法一:树状数组** |
78 | 78 |
|
79 | 79 | 树状数组,也称作“二叉索引树”(Binary Indexed Tree)或 Fenwick 树。 它可以高效地实现如下两个操作:
|
80 | 80 |
|
|
89 | 89 |
|
90 | 90 | 解决方案是直接遍历数组,每个位置先求出 `query(a[i])`,然后再修改树状数组 `update(a[i], 1)` 即可。当数的范围比较大时,需要进行离散化,即先进行去重并排序,然后对每个数字进行编号。
|
91 | 91 |
|
| 92 | +**方法二:线段树** |
| 93 | + |
| 94 | +Python3 代码 TLE,Java、C++ 代码 AC。 |
| 95 | + |
92 | 96 | <!-- tabs:start -->
|
93 | 97 |
|
94 | 98 | ### **Python3**
|
95 | 99 |
|
96 | 100 | <!-- 这里可写当前语言的特殊实现逻辑 -->
|
97 | 101 |
|
| 102 | +树状数组: |
| 103 | + |
98 | 104 | ```python
|
99 | 105 | class BinaryIndexedTree:
|
100 | 106 | def __init__(self, n):
|
@@ -131,10 +137,73 @@ class Solution:
|
131 | 137 | return ans % int((1e9 + 7))
|
132 | 138 | ```
|
133 | 139 |
|
| 140 | +线段树: |
| 141 | + |
| 142 | +```python |
| 143 | +class Node: |
| 144 | + def __init__(self): |
| 145 | + self.l = 0 |
| 146 | + self.r = 0 |
| 147 | + self.v = 0 |
| 148 | + |
| 149 | +class SegmentTree: |
| 150 | + def __init__(self, n): |
| 151 | + self.tr = [Node() for _ in range(4 * n)] |
| 152 | + self.build(1, 1, n) |
| 153 | + |
| 154 | + def build(self, u, l, r): |
| 155 | + self.tr[u].l = l |
| 156 | + self.tr[u].r = r |
| 157 | + if l == r: |
| 158 | + return |
| 159 | + mid = (l + r) >> 1 |
| 160 | + self.build(u << 1, l, mid) |
| 161 | + self.build(u << 1 | 1, mid + 1, r) |
| 162 | + |
| 163 | + def modify(self, u, x, v): |
| 164 | + if self.tr[u].l == x and self.tr[u].r == x: |
| 165 | + self.tr[u].v += v |
| 166 | + return |
| 167 | + mid = (self.tr[u].l + self.tr[u].r) >> 1 |
| 168 | + if x <= mid: |
| 169 | + self.modify(u << 1, x, v) |
| 170 | + else: |
| 171 | + self.modify(u << 1 | 1, x, v) |
| 172 | + self.pushup(u) |
| 173 | + |
| 174 | + def pushup(self, u): |
| 175 | + self.tr[u].v = self.tr[u << 1].v + self.tr[u << 1 | 1].v |
| 176 | + |
| 177 | + def query(self, u, l, r): |
| 178 | + if self.tr[u].l >= l and self.tr[u].r <= r: |
| 179 | + return self.tr[u].v |
| 180 | + mid = (self.tr[u].l + self.tr[u].r) >> 1 |
| 181 | + v = 0 |
| 182 | + if l <= mid: |
| 183 | + v = self.query(u << 1, l, r) |
| 184 | + if r > mid: |
| 185 | + v += self.query(u << 1 | 1, l, r) |
| 186 | + return v |
| 187 | + |
| 188 | +class Solution: |
| 189 | + def createSortedArray(self, instructions: List[int]) -> int: |
| 190 | + n = max(instructions) |
| 191 | + tree = SegmentTree(n) |
| 192 | + ans = 0 |
| 193 | + for num in instructions: |
| 194 | + a = tree.query(1, 1, num - 1) |
| 195 | + b = tree.query(1, 1, n) - tree.query(1, 1, num) |
| 196 | + ans += min(a, b) |
| 197 | + tree.modify(1, num, 1) |
| 198 | + return ans % int((1e9 + 7)) |
| 199 | +``` |
| 200 | + |
134 | 201 | ### **Java**
|
135 | 202 |
|
136 | 203 | <!-- 这里可写当前语言的特殊实现逻辑 -->
|
137 | 204 |
|
| 205 | +树状数组: |
| 206 | + |
138 | 207 | ```java
|
139 | 208 | class Solution {
|
140 | 209 | public int createSortedArray(int[] instructions) {
|
@@ -184,8 +253,93 @@ class BinaryIndexedTree {
|
184 | 253 | }
|
185 | 254 | ```
|
186 | 255 |
|
| 256 | +线段树: |
| 257 | + |
| 258 | +```java |
| 259 | +class Solution { |
| 260 | + public int createSortedArray(int[] instructions) { |
| 261 | + int n = 100010; |
| 262 | + int mod = (int) 1e9 + 7; |
| 263 | + SegmentTree tree = new SegmentTree(n); |
| 264 | + int ans = 0; |
| 265 | + for (int num : instructions) { |
| 266 | + int a = tree.query(1, 1, num - 1); |
| 267 | + int b = tree.query(1, 1, n) - tree.query(1, 1, num); |
| 268 | + ans += Math.min(a, b); |
| 269 | + ans %= mod; |
| 270 | + tree.modify(1, num, 1); |
| 271 | + } |
| 272 | + return ans; |
| 273 | + } |
| 274 | +} |
| 275 | + |
| 276 | +class Node { |
| 277 | + int l; |
| 278 | + int r; |
| 279 | + int v; |
| 280 | +} |
| 281 | + |
| 282 | +class SegmentTree { |
| 283 | + private Node[] tr; |
| 284 | + |
| 285 | + public SegmentTree(int n) { |
| 286 | + tr = new Node[4 * n]; |
| 287 | + for (int i = 0; i < tr.length; ++i) { |
| 288 | + tr[i] = new Node(); |
| 289 | + } |
| 290 | + build(1, 1, n); |
| 291 | + } |
| 292 | + |
| 293 | + public void build(int u, int l, int r) { |
| 294 | + tr[u].l = l; |
| 295 | + tr[u].r = r; |
| 296 | + if (l == r) { |
| 297 | + return; |
| 298 | + } |
| 299 | + int mid = (l + r) >> 1; |
| 300 | + build(u << 1, l, mid); |
| 301 | + build(u << 1 | 1, mid + 1, r); |
| 302 | + } |
| 303 | + |
| 304 | + public void modify(int u, int x, int v) { |
| 305 | + if (tr[u].l == x && tr[u].r == x) { |
| 306 | + tr[u].v += v; |
| 307 | + return; |
| 308 | + } |
| 309 | + int mid = (tr[u].l + tr[u].r) >> 1; |
| 310 | + if (x <= mid) { |
| 311 | + modify(u << 1, x, v); |
| 312 | + } else { |
| 313 | + modify(u << 1 | 1, x, v); |
| 314 | + } |
| 315 | + pushup(u); |
| 316 | + } |
| 317 | + |
| 318 | + public void pushup(int u) { |
| 319 | + tr[u].v = tr[u << 1].v + tr[u << 1 | 1].v; |
| 320 | + } |
| 321 | + |
| 322 | + public int query(int u, int l, int r) { |
| 323 | + if (tr[u].l >= l && tr[u].r <= r) { |
| 324 | + return tr[u].v; |
| 325 | + } |
| 326 | + int mid = (tr[u].l + tr[u].r) >> 1; |
| 327 | + int v = 0; |
| 328 | + if (l <= mid) { |
| 329 | + v += query(u << 1, l, r); |
| 330 | + } |
| 331 | + if (r > mid) { |
| 332 | + v += query(u << 1 | 1, l, r); |
| 333 | + } |
| 334 | + return v; |
| 335 | + } |
| 336 | +} |
| 337 | +``` |
| 338 | + |
187 | 339 | ### **C++**
|
188 | 340 |
|
| 341 | +树状数组: |
| 342 | + |
189 | 343 | ```cpp
|
190 | 344 | class BinaryIndexedTree {
|
191 | 345 | public:
|
@@ -237,8 +391,85 @@ public:
|
237 | 391 | };
|
238 | 392 | ```
|
239 | 393 |
|
| 394 | +线段树: |
| 395 | +
|
| 396 | +```cpp |
| 397 | +class Node { |
| 398 | +public: |
| 399 | + int l; |
| 400 | + int r; |
| 401 | + int v; |
| 402 | +}; |
| 403 | +
|
| 404 | +class SegmentTree { |
| 405 | +public: |
| 406 | + vector<Node*> tr; |
| 407 | +
|
| 408 | + SegmentTree(int n) { |
| 409 | + tr.resize(4 * n); |
| 410 | + for (int i = 0; i < tr.size(); ++i) tr[i] = new Node(); |
| 411 | + build(1, 1, n); |
| 412 | + } |
| 413 | +
|
| 414 | + void build(int u, int l, int r) { |
| 415 | + tr[u]->l = l; |
| 416 | + tr[u]->r = r; |
| 417 | + if (l == r) return; |
| 418 | + int mid = (l + r) >> 1; |
| 419 | + build(u << 1, l, mid); |
| 420 | + build(u << 1 | 1, mid + 1, r); |
| 421 | + } |
| 422 | +
|
| 423 | + void modify(int u, int x, int v) { |
| 424 | + if (tr[u]->l == x && tr[u]->r == x) |
| 425 | + { |
| 426 | + tr[u]->v += v; |
| 427 | + return; |
| 428 | + } |
| 429 | + int mid = (tr[u]->l + tr[u]->r) >> 1; |
| 430 | + if (x <= mid) modify(u << 1, x, v); |
| 431 | + else modify(u << 1 | 1, x, v); |
| 432 | + pushup(u); |
| 433 | + } |
| 434 | +
|
| 435 | + void pushup(int u) { |
| 436 | + tr[u]->v = tr[u << 1]->v + tr[u << 1 | 1]->v; |
| 437 | + } |
| 438 | +
|
| 439 | + int query(int u, int l, int r) { |
| 440 | + if (tr[u]->l >= l && tr[u]->r <= r) return tr[u]->v; |
| 441 | + int mid = (tr[u]->l + tr[u]->r) >> 1; |
| 442 | + int v = 0; |
| 443 | + if (l <= mid) v = query(u << 1, l, r); |
| 444 | + if (r > mid) v += query(u << 1 | 1, l, r); |
| 445 | + return v; |
| 446 | + } |
| 447 | +}; |
| 448 | +
|
| 449 | +class Solution { |
| 450 | +public: |
| 451 | + int createSortedArray(vector<int>& instructions) { |
| 452 | + int n = *max_element(instructions.begin(), instructions.end()); |
| 453 | + int mod = 1e9 + 7; |
| 454 | + SegmentTree* tree = new SegmentTree(n); |
| 455 | + int ans = 0; |
| 456 | + for (int num : instructions) |
| 457 | + { |
| 458 | + int a = tree->query(1, 1, num - 1); |
| 459 | + int b = tree->query(1, 1, n) - tree->query(1, 1, num); |
| 460 | + ans += min(a, b); |
| 461 | + ans %= mod; |
| 462 | + tree->modify(1, num, 1); |
| 463 | + } |
| 464 | + return ans; |
| 465 | + } |
| 466 | +}; |
| 467 | +``` |
| 468 | + |
240 | 469 | ### **Go**
|
241 | 470 |
|
| 471 | +树状数组: |
| 472 | + |
242 | 473 | ```go
|
243 | 474 | type BinaryIndexedTree struct {
|
244 | 475 | n int
|
|
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