week 3 homework

Author: xuyunbo

Week_03/id_90/LeetCode_703_090.java

@@ -0,0 +1,47 @@
+import com.eclipsesource.json.JsonArray;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.PriorityQueue;
+
+/**
+ *
+ */
+class KthLargest {
+    int size;
+    PriorityQueue < Integer > minheap;
+    public KthLargest(int k, int[] nums) {
+        minheap = new PriorityQueue < > (k + 1);
+        size = k;
+        for (int num: nums) {
+            minheap.offer(num);
+            if (minheap.size() > k) minheap.poll();
+        }
+    }
+
+    public int add(int val) {
+        if (minheap.isEmpty() || minheap.size() < size) minheap.offer(val);
+        else if (val >= minheap.peek()) {
+            minheap.offer(val);
+        }
+        if (minheap.size() > size) minheap.poll();
+        return minheap.peek();
+    }
+}
+
+public class TestHeap {
+    public static void main(String[] args) {
+        int[] arr = {
+            4,
+            5,
+            8,
+            2
+        };
+        KthLargest kthLargest = new KthLargest(3, arr);
+        int add1 = kthLargest.add(3);
+        int add2 = kthLargest.add(5);
+        System.out.println(add1);
+        System.out.println(add2);
+    }
+}

Week_03/id_90/LeetCode_997_090.java

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+import com.eclipsesource.json.JsonArray;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+/**
+ *
+ */
+class SolutionGraph {
+    public int findJudge(int N, int[][] trust) {
+        //记录每个人被人相信的次数
+        int[] outgoing = new int[N+1];
+        //记录每个人相信别人的次数
+        int[] incoming = new int[N+1];
+        for(int i=0; i<trust.length; i++) {
+            int o = trust[i][0];
+            int in = trust[i][1];
+            outgoing[o] += 1;
+            incoming[in] += 1;
+        }
+        for(int i=1; i<N+1; i++) {
+            //相信i的人N-1个且i相信的人为0
+            if(incoming[i] == N-1 && outgoing[i] == 0)
+                return i;
+        }
+        return -1;
+    }
+}
+
+public class TestGraph {
+    public static int[] stringToIntegerArray(String input) {
+        input = input.trim();
+        input = input.substring(1, input.length() - 1);
+        if (input.length() == 0) {
+            return new int[0];
+        }
+
+        String[] parts = input.split(",");
+        int[] output = new int[parts.length];
+        for(int index = 0; index < parts.length; index++) {
+            String part = parts[index].trim();
+            output[index] = Integer.parseInt(part);
+        }
+        return output;
+    }
+
+    public static int[][] stringToInt2dArray(String input) {
+        JsonArray jsonArray = JsonArray.readFrom(input);
+        if (jsonArray.size() == 0) {
+            return new int[0][0];
+        }
+
+        int[][] arr = new int[jsonArray.size()][];
+        for (int i = 0; i < arr.length; i++) {
+            JsonArray cols = jsonArray.get(i).asArray();
+            arr[i] = stringToIntegerArray(cols.toString());
+        }
+        return arr;
+    }
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
+        String line;
+        while ((line = in.readLine()) != null) {
+            int N = Integer.parseInt(line);
+            line = in.readLine();
+            int[][] trust = stringToInt2dArray(line);
+            int ret = new SolutionGraph().findJudge(N, trust);
+            String out = String.valueOf(ret);
+            System.out.print(out);
+        }
+    }
+}