49 lines
1.3 KiB
Java
49 lines
1.3 KiB
Java
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package graph;
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/**
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* 题目： 200. 岛屿数量 (numIslands)
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* 描述：给你一个由 '1'（陆地）和 '0'（水）组成的的二维网格，请你计算网格中岛屿的数量。
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* 岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。
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* 此外，你可以假设该网格的四条边均被水包围。
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* 链接：https://leetcode.cn/problems/number-of-islands/
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*/
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public class NumIslands {
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void dfs(char[][] grid, int r, int c) {
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int nr = grid.length;
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int nc = grid[0].length;
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if (r < 0 || c < 0 || r >= nr || c >= nc || grid[r][c] == '0') {
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return;
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}
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grid[r][c] = '0';
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dfs(grid, r - 1, c);
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dfs(grid, r + 1, c);
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dfs(grid, r, c - 1);
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dfs(grid, r, c + 1);
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}
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public int numIslands(char[][] grid) {
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if (grid == null || grid.length == 0) {
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return 0;
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}
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int nr = grid.length;
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int nc = grid[0].length;
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int num_islands = 0;
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for (int r = 0; r < nr; ++r) {
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for (int c = 0; c < nc; ++c) {
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if (grid[r][c] == '1') {
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++num_islands;
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dfs(grid, r, c);
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}
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}
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}
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return num_islands;
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}
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}
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