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-rw-r--r--number_islands.cpp30
1 files changed, 30 insertions, 0 deletions
diff --git a/number_islands.cpp b/number_islands.cpp
new file mode 100644
index 0000000..96b8e0b
--- /dev/null
+++ b/number_islands.cpp
@@ -0,0 +1,30 @@
+#include "leetcode.h"
+
+class Solution {
+public:
+ int numIslands(vector<vector<char>> &grid) {
+ int islands = 0;
+ for (int i = 0; i < grid.size(); i++) {
+ for (int j = 0; j < grid[0].size(); j++) {
+ if (grid[i][j] == '1') {
+ dfs(grid, i, j);
+ ++islands;
+ }
+ }
+ }
+ return islands;
+ }
+
+private:
+ void dfs(vector<vector<char>> &grid, int i, int j) {
+ if (i < 0 || i >= grid.size() || j < 0 || j >= grid[0].size())
+ return;
+ if (grid[i][j] == '2' || grid[i][j] == '0')
+ return;
+ grid[i][j] = '2';
+ dfs(grid, i + 1, j);
+ dfs(grid, i, j + 1);
+ dfs(grid, i - 1, j);
+ dfs(grid, i, j + 1);
+ }
+};