Add Q199, Q200

Author: theFool32

199_BinaryTreeRightSideView/BinaryTreeRightSideView.cc

@@ -0,0 +1,31 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<int> rightSideView(TreeNode* root) {
+        queue<TreeNode*> q[2];
+        vector<int> res;
+        if (!root) return res;
+
+        int l = 0;
+        q[0].push(root);
+        while (!q[0].empty() || !q[1].empty()) {
+            while (!q[l].empty()) {
+                TreeNode *temp = q[l].front();
+                q[l].pop();
+                if (temp->left) q[1-l].push(temp->left);
+                if (temp->right) q[1-l].push(temp->right);
+                if (q[l].empty()) res.push_back(temp->val);
+            }
+            l = 1-l;
+        }
+        return res;
+    }
+};

200_NumberOfIslands/NumberOfIslands.cc

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    int numIslands(vector<vector<char>>& grid) {
+        int ans = 0;
+        int m = grid.size(); 
+        if (m == 0) return ans;
+        int n = grid[0].size();
+        function<void(int,int)> change = [&](int i, int j)-> void {
+            if (i >= 0 && i < m && j >=0 && j < n && grid[i][j] == '1') {
+                grid[i][j] = '0';
+                change(i-1,j);
+                change(i+1,j);
+                change(i,j-1);
+                change(i,j+1);
+            }
+        };
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == '1') {
+                    ++ans;
+                    change(i, j);
+                }
+            }
+        }
+        return ans;
+    }
+};
+