完成710

Author: diguage

README.adoc

@@ -4988,14 +4988,14 @@ TIP: **公众号的微信号是: `jikerizhi`**。__因为众所周知的原因
 //|{doc_base_url}/0709-to-lower-case.adoc[题解]
 //|Easy
 //|
-//
-//|710
-//|{leetcode_base_url}/random-pick-with-blacklist/[Random Pick with Blacklist]
-//|{source_base_url}/_0710_RandomPickWithBlacklist.java[Java]
-//|{doc_base_url}/0710-random-pick-with-blacklist.adoc[题解]
-//|Hard
-//|
-//
+
+|710
+|{leetcode_base_url}/random-pick-with-blacklist/[Random Pick with Blacklist]
+|{source_base_url}/_0710_RandomPickWithBlacklist.java[Java]
+|{doc_base_url}/0710-random-pick-with-blacklist.adoc[题解]
+|Hard
+|
+
 //|711
 //|{leetcode_base_url}/number-of-distinct-islands-ii/[Number of Distinct Islands II]
 //|{source_base_url}/_0711_NumberOfDistinctIslandsII.java[Java]

docs/0710-random-pick-with-blacklist.adoc

@@ -59,7 +59,11 @@ Optimize it such that it minimizes the call to system’s `Math.random()`.
 
 The input is two lists: the subroutines called and their arguments. `Solution`'s constructor has two arguments, `N` and the blacklist `B`. `pick` has no arguments. Arguments are always wrapped with a list, even if there aren't any.
 
+== 思路分析
 
+image::images/0710-01.png[{image_attr}]
+
+image::images/0710-02.png[{image_attr}]
 
 [[src-0710]]
 [{java_src_attr}]

docs/images/0710-01.png

@@ -244,5 +244,10 @@
 |{doc_base_url}/0380-insert-delete-getrandom-o1.adoc[题解]
 |数据结构应用
 
+|710
+|{leetcode_base_url}/random-pick-with-blacklist/[Random Pick with Blacklist]
+|{doc_base_url}/0710-random-pick-with-blacklist.adoc[题解]
+|把映射处理好
+
 
 |===

docs/images/0710-02.png

@@ -0,0 +1,49 @@
+package com.diguage.algorithm.leetcode;
+
+import java.util.*;
+
+public class _0710_RandomPickWithBlacklist {
+  class Solution {
+    Map<Integer, Integer> b2w;
+    Random random;
+    int size;
+
+    /**
+     * 把黑名单都放在最后
+     */
+    public Solution(int n, int[] blacklist) {
+      size = n - blacklist.length;
+      random = new Random();
+      b2w = new HashMap<>();
+      List<Integer> sb = new ArrayList<>();
+      List<Integer> bw = new ArrayList<>();
+      Set<Integer> bb = new HashSet<>();
+      for (int i = 0; i < blacklist.length; i++) {
+        int b = blacklist[i];
+        // 按照界限，把黑名单数字按照大小分开
+        if (b >= size) {
+          bb.add(b);
+        } else {
+          sb.add(b);
+        }
+      }
+      for (int i = n - 1; i >= size; i--) {
+        // 从最后的数字里找出不是黑名单的数字
+        if (!bb.contains(i)) {
+          bw.add(i);
+        }
+      }
+      // 建立起黑→白的对应关系
+      while (!sb.isEmpty() && !bw.isEmpty()) {
+        Integer b = sb.remove(sb.size() - 1);
+        Integer w = bw.remove(bw.size() - 1);
+        b2w.put(b, w);
+      }
+    }
+
+    public int pick() {
+      int val = random.nextInt(size);
+      return b2w.getOrDefault(val, val);
+    }
+  }
+}