algorithm007-class01
diff --git a/Week_07/G20200343040145/LeetCode_200_0145.java b/Week_07/G20200343040145/LeetCode_200_0145.java
@@ -0,0 +1,55 @@
+import java.util.Arrays;
+
+public class LeetCode_200_0145 {
+    public int numIslands(char[][] grid) {
+        if(grid.length == 0) return 0;
+        int x = grid.length;
+        int y = grid[0].length;
+
+        int[] nums = new int[x * y];
+        Arrays.fill(nums, -1);
+
+        for(int i = 0; i < x; i++) {
+            for(int j = 0; j < y; j++) {
+                if(grid[i][j] == '1') {
+                    grid[i][j] = '0';
+
+                    //判断下侧是否有陆地
+                    if(i < (x - 1) && grid[i + 1][j] == '1') {
+                        union(nums, i * y + j, (i + 1) * y + j);
+                    }
+
+                    //判断右侧是否有陆地
+                    if(j < (y - 1) && grid[i][j + 1] == '1') {
+                        union(nums, i * y + j, i * y + j + 1);
+                    }
+                } else {
+                    nums[i * y + j] = -2;
+                }
+            }
+        }
+
+        int count = 0;
+        for(int num : nums) {
+            if(num == -1) count++;
+        }
+
+        return count;
+    }
+
+    public int find(int[] parents, int i) {
+        if(parents[i] == -1) {
+            return i;
+        }
+
+        return find(parents, parents[i]);
+    }
+
+    public void union(int[] parents, int x, int y) {
+        int xset = find(parents, x);
+        int yset = find(parents, y);
+        if(xset != yset) {
+            parents[xset] = yset;
+        }
+    }
+}
diff --git a/Week_07/G20200343040145/LeetCode_547_0145.java b/Week_07/G20200343040145/LeetCode_547_0145.java
@@ -0,0 +1,29 @@
+public class LeetCode_547_0145 {
+
+    public int findCircleNum(int[][] M) {
+        int peopleCount = M.length;
+        //
+        int[] visited = new int[peopleCount];
+
+        int circleCount = 0;
+        for (int curPeople = 0; curPeople < peopleCount; curPeople++){
+            // 当前同学未统计过
+            if (visited[curPeople] == 0){
+                recursion(M, visited, curPeople, peopleCount);
+                circleCount++;
+            }
+        }
+
+        return circleCount;
+    }
+
+    private void recursion(int[][] M, int[] visited, int curPeople, int peopleCount){
+        for (int recurPeople = 0; recurPeople < peopleCount; recurPeople++){
+            if (M[curPeople][recurPeople] == 1 && visited[recurPeople] == 0){
+                visited[recurPeople] = 1;
+                recursion(M, visited, recurPeople, peopleCount);
+            }
+        }
+    }
+
+}
diff --git a/Week_08/G20200343040145/LeetCode_0190_0145.java b/Week_08/G20200343040145/LeetCode_0190_0145.java
@@ -0,0 +1,17 @@
+public class LeetCode_0190_0145 {
+    /**
+     * 二进制反转
+     *  10001 => 从右往左 (1 * 2^4) + (0 * 2 ^3) + (0 * 2^2) + (0 * 2^1) + (0 * 2^0)
+     * */
+    public int reverseBits(int n) {
+        int pow = 31;
+        int res = 0;
+        while (n != 0 & pow >= 0) {
+            // 最后一位的值 乘以 幂次
+            res += (n & 1) << pow;
+            pow -= 1;
+            n >>>= 1;
+        }
+        return res;
+    }
+}
diff --git a/Week_08/G20200343040145/LeetCode_0191_0145.java b/Week_08/G20200343040145/LeetCode_0191_0145.java
@@ -0,0 +1,30 @@
+public class LeetCode_0191_0145 {
+    /**
+     * 按位与 计算 二进制中 1 的数量
+     * */
+    private int hammingWeightTwo(int n) {
+        int cnt = 0;
+        while (n  != 0) {
+            cnt += 1;
+            n = n & (n - 1);
+        }
+        return cnt;
+    }
+
+    /**
+     * 方法① 循环遍历
+     * */
+    public int hammingWeightOne(int n) {
+        // 掩码
+        int mask = 1;
+        // 数量
+        int cnt = 0;
+        for (int i = 0; i < 32; i++) {
+            if ((n & mask) != 0) {
+                cnt += 1;
+            }
+            mask <<= 1;
+        }
+        return cnt;
+    }
+}
diff --git a/Week_08/G20200343040145/LeetCode_0231_0145.java b/Week_08/G20200343040145/LeetCode_0231_0145.java
@@ -0,0 +1,11 @@
+public class LeetCode_0231_0145 {
+    /**
+     * 计算是否时 2 的幂次
+     * */
+    public boolean isPowerOfTwo(int n) {
+        // 1.根据 条件 n >0 排除了 0000000001的情况
+        // 2.n & (n-1) = 0 代表 二进制中 1 的个数 为 1 个
+        // 00000000001000  & 00000000000111 = 0 符合条件
+        return n > 0 && (n & (n - 1)) == 0;
+    }
+}
diff --git a/Week_08/G20200343040145/LeetCode_190_0145.java b/Week_08/G20200343040145/LeetCode_190_0145.java
@@ -0,0 +1,17 @@
+public class LeetCode_190_0145 {
+    /**
+     * 二进制反转
+     *  10001 => 从右往左 (1 * 2^4) + (0 * 2 ^3) + (0 * 2^2) + (0 * 2^1) + (0 * 2^0)
+     * */
+    public int reverseBits(int n) {
+        int pow = 31;
+        int res = 0;
+        while (n != 0 & pow >= 0) {
+            // 最后一位的值 乘以 幂次
+            res += (n & 1) << pow;
+            pow -= 1;
+            n >>>= 1;
+        }
+        return res;
+    }
+}
diff --git a/Week_08/G20200343040145/LeetCode_191_0145.java b/Week_08/G20200343040145/LeetCode_191_0145.java
@@ -0,0 +1,30 @@
+public class LeetCode_191_0145 {
+    /**
+     * 按位与 计算 二进制中 1 的数量
+     * */
+    private int hammingWeightTwo(int n) {
+        int cnt = 0;
+        while (n  != 0) {
+            cnt += 1;
+            n = n & (n - 1);
+        }
+        return cnt;
+    }
+
+    /**
+     * 方法① 循环遍历
+     * */
+    public int hammingWeightOne(int n) {
+        // 掩码
+        int mask = 1;
+        // 数量
+        int cnt = 0;
+        for (int i = 0; i < 32; i++) {
+            if ((n & mask) != 0) {
+                cnt += 1;
+            }
+            mask <<= 1;
+        }
+        return cnt;
+    }
+}
diff --git a/Week_08/G20200343040145/LeetCode_231_0145.java b/Week_08/G20200343040145/LeetCode_231_0145.java
@@ -0,0 +1,11 @@
+public class LeetCode_231_0145 {
+    /**
+     * 计算是否时 2 的幂次
+     * */
+    public boolean isPowerOfTwo(int n) {
+        // 1.根据 条件 n >0 排除了 0000000001的情况
+        // 2.n & (n-1) = 0 代表 二进制中 1 的个数 为 1 个
+        // 00000000001000  & 00000000000111 = 0 符合条件
+        return n > 0 && (n & (n - 1)) == 0;
+    }
+}