已交

.gitignore

@@ -22,4 +22,8 @@ output/
 Thumbs.db
 
 # 排除竞赛平台配置文件
-.cph/
+.cph/
+
+# 排除作业相关目录
+作业/刘航宇-day*
+作业/提交/

exercise/src/Main.java

@@ -3,41 +3,30 @@ import java.util.Scanner;
 public class Main {
     public static void main(String[] args) {
         Scanner in = new Scanner(System.in);
-        int n = in.nextInt();
-        int[] mention = new int[101];
-        boolean[][] by = new boolean[101][101];
-        for (int i = 0; i < n; i++) {
-            int sender = in.nextInt();
-            int k = in.nextInt();
-            for (int j = 0; j < k; j++) {
-                int id = in.nextInt();
-                if (id >= 0 && id <= 100) {
-                    mention[id]++;
-                    if (sender >= 0 && sender <= 100)
-                        by[id][sender] = true;
+        if (in.hasNextInt()) {
+            int n = in.nextInt();
+            int[] arr = new int[n];
+            for (int i = 0; i < n; i++) {
+                arr[i] = in.nextInt();
+            }
+
+            // 题目要求计算最少交换次数，即逆序对的数量
+            // 使用冒泡排序的交换次数来统计
+            int swaps = 0;
+            for (int i = 0; i < n - 1; i++) {
+                for (int j = 0; j < n - 1 - i; j++) {
+                    if (arr[j] > arr[j + 1]) {
+                        // 交换
+                        int temp = arr[j];
+                        arr[j] = arr[j + 1];
+                        arr[j + 1] = temp;
+                        swaps++;
+                    }
                 }
             }
+
+            System.out.println(swaps);
         }
-        int bestId = 0;
-        int bestCount = -1;
-        for (int id = 0; id <= 100; id++) {
-            if (mention[id] > bestCount) {
-                bestCount = mention[id];
-                bestId = id;
-            }
-        }
-        System.out.println(bestId);
-        StringBuilder sb = new StringBuilder();
-        boolean first = true;
-        for (int s = 0; s <= 100; s++) {
-            if (by[bestId][s]) {
-                if (!first)
-                    sb.append(' ');
-                sb.append(s);
-                first = false;
-            }
-        }
-        System.out.println(sb.toString());
         in.close();
     }
 }

作业/作业/刘航宇-day47/第一题/Main.java

@@ -0,0 +1,31 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        if (in.hasNextLine()) {
+            String s1 = in.nextLine();
+            if (in.hasNextLine()) {
+                String s2 = in.nextLine();
+
+                String longer, shorter;
+                if (s1.length() >= s2.length()) {
+                    longer = s1;
+                    shorter = s2;
+                } else {
+                    longer = s2;
+                    shorter = s1;
+                }
+
+                // 将短的字符串内容覆盖到长的字符串内（从头开始）
+                StringBuilder sb = new StringBuilder(longer);
+                for (int i = 0; i < shorter.length(); i++) {
+                    sb.setCharAt(i, shorter.charAt(i));
+                }
+
+                System.out.println(sb.toString());
+            }
+        }
+        in.close();
+    }
+}

作业/作业/刘航宇-day47/第三题/Main.java

@@ -0,0 +1,32 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        if (in.hasNextInt()) {
+            int n = in.nextInt();
+            int[] arr = new int[n];
+            for (int i = 0; i < n; i++) {
+                arr[i] = in.nextInt();
+            }
+
+            // 题目要求计算最少交换次数，即逆序对的数量
+            // 使用冒泡排序的交换次数来统计
+            int swaps = 0;
+            for (int i = 0; i < n - 1; i++) {
+                for (int j = 0; j < n - 1 - i; j++) {
+                    if (arr[j] > arr[j + 1]) {
+                        // 交换
+                        int temp = arr[j];
+                        arr[j] = arr[j + 1];
+                        arr[j + 1] = temp;
+                        swaps++;
+                    }
+                }
+            }
+
+            System.out.println(swaps);
+        }
+        in.close();
+    }
+}

作业/作业/刘航宇-day47/第二题/Main.java

@@ -0,0 +1,39 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        if (in.hasNextInt()) {
+            int n = in.nextInt();
+            int t = in.nextInt();
+
+            int[] a = new int[n];
+            for (int i = 0; i < n; i++) {
+                a[i] = in.nextInt();
+            }
+
+            int[] b = new int[n];
+            for (int i = 0; i < n; i++) {
+                b[i] = in.nextInt();
+            }
+
+            // 贪心策略：将 A 升序排序，B 升序排序
+            // 然后将 A 中最小的与 B 中最大的配对
+            Arrays.sort(a);
+            Arrays.sort(b);
+
+            long totalOvertime = 0;
+            for (int i = 0; i < n; i++) {
+                // A[i] 配对 B[n - 1 - i]
+                int time = a[i] + b[n - 1 - i];
+                if (time > t) {
+                    totalOvertime += (time - t);
+                }
+            }
+
+            System.out.println(totalOvertime);
+        }
+        in.close();
+    }
+}

作业/作业/刘航宇-day48/第三题/Main.java

@@ -0,0 +1,106 @@
+import java.util.Scanner;
+
+public class Main {
+    static final long MOD = 1000000007;
+    static long[] powerOf10;
+    static Node[][][] memo;
+    static int[] digits;
+
+    static class Node {
+        long cnt;
+        long sum;
+        long sqSum;
+
+        public Node(long c, long s, long sq) {
+            this.cnt = c;
+            this.sum = s;
+            this.sqSum = sq;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        // 初始化10的幂次
+        powerOf10 = new long[20];
+        powerOf10[0] = 1;
+        for (int i = 1; i < 20; i++) {
+            powerOf10[i] = (powerOf10[i - 1] * 10) % MOD;
+        }
+
+        if (in.hasNextLong()) {
+            long l = in.nextLong();
+            long r = in.nextLong();
+            long ans = (solve(r) - solve(l - 1) + MOD) % MOD;
+            System.out.println(ans);
+        }
+        in.close();
+    }
+
+    static long solve(long n) {
+        if (n == 0)
+            return 0;
+        String s = String.valueOf(n);
+        int len = s.length();
+        digits = new int[len];
+        for (int i = 0; i < len; i++) {
+            digits[i] = s.charAt(len - 1 - i) - '0';
+        }
+
+        // 重置memo
+        memo = new Node[len + 1][7][7];
+
+        Node res = dfs(len - 1, 0, 0, true);
+        return res.sqSum;
+    }
+
+    static Node dfs(int pos, int valRem, int sumRem, boolean limit) {
+        if (pos < 0) {
+            // 如果数字本身不是7的倍数，且各位数字之和不是7的倍数，则有效
+            // (含7的情况已在循环中跳过)
+            if (valRem != 0 && sumRem != 0) {
+                return new Node(1, 0, 0);
+            }
+            return new Node(0, 0, 0);
+        }
+        if (!limit && memo[pos][valRem][sumRem] != null) {
+            return memo[pos][valRem][sumRem];
+        }
+
+        int up = limit ? digits[pos] : 9;
+        long cnt = 0;
+        long sum = 0;
+        long sqSum = 0;
+
+        for (int d = 0; d <= up; d++) {
+            if (d == 7)
+                continue; // 跳过含7的情况
+
+            Node next = dfs(pos - 1, (valRem * 10 + d) % 7, (sumRem + d) % 7, limit && (d == up));
+
+            if (next.cnt > 0) {
+                long p = powerOf10[pos];
+                long val = (d * p) % MOD;
+                long val2 = (val * val) % MOD;
+
+                // 更新计数
+                cnt = (cnt + next.cnt) % MOD;
+
+                // 更新和: sum += next.sum + val * next.cnt
+                long termSum = (val * next.cnt) % MOD;
+                sum = (sum + next.sum + termSum) % MOD;
+
+                // 更新平方和: sqSum += next.sqSum + 2 * val * next.sum + val^2 * next.cnt
+                long termSq1 = next.sqSum;
+                long termSq2 = (2 * val % MOD * next.sum) % MOD;
+                long termSq3 = (val2 * next.cnt) % MOD;
+                sqSum = (sqSum + termSq1 + termSq2 + termSq3) % MOD;
+            }
+        }
+
+        Node res = new Node(cnt, sum, sqSum);
+        if (!limit) {
+            memo[pos][valRem][sumRem] = res;
+        }
+        return res;
+    }
+}

作业/作业/刘航宇-day48/第二题/Main.java

@@ -0,0 +1,18 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        if (in.hasNext()) {
+            String s1 = in.next();
+            if (in.hasNext()) {
+                String s2 = in.next();
+                BigInteger a = new BigInteger(s1);
+                BigInteger b = new BigInteger(s2);
+                System.out.println(a.add(b));
+            }
+        }
+        in.close();
+    }
+}