[剑指offer]矩阵中的路径_visited = new boolean[matrix.length];-优快云博客

本文链接：https://blog.youkuaiyun.com/u014559071/article/details/78755260

本文介绍了一个Java方法，用于在一个字符矩阵中寻找特定字符串是否存在。通过深度优先搜索算法遍历矩阵，检查目标字符串是否能从任意位置开始匹配。文章详细展示了递归函数实现，并使用布尔数组记录已访问过的矩阵元素。

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public class Solution {
	public boolean hasPath(char[] matrix, int rows, int cols, char[] str) {
		//为空情况
		if (matrix.length == 0 || str.length == 0) {
			return false;
		}
		//是否访问过 默认false
		boolean[] visited = new boolean[matrix.length];
		int pathlength = 0;
		//字串下标
		//双重循环检测
		for (int row = 0; row < rows; row++) {
			for (int col = 0; col < cols; col++) {
				if (hasPathCore(matrix, rows, cols, row, col, str, pathlength, visited)) {
					return true;
				}
			}
		}
		return false;
	}

	public boolean hasPathCore(char[] matrix, int rows, int cols, int row, int col, char[] str, int pathlength,
			boolean[] visited) {

		int index = row * cols + col;
		//长字符串下标
		if (pathlength == str.length)
			return true;
		//越界返回true 越界说明找到 访问完了
		if (row < 0 || row >= rows || col < 0 || col >= cols || matrix[index] != str[pathlength]
				|| visited[index] == true)
			return false;
		//查找失败返回false

		visited[index] = true;
		//标记访问过
		
		//访问上下左右 递归回溯
		if (hasPathCore(matrix, rows, cols, row, col - 1, str, pathlength + 1, visited)
				|| hasPathCore(matrix, rows, cols, row, col + 1, str, pathlength + 1, visited)
				|| hasPathCore(matrix, rows, cols, row - 1, col, str, pathlength + 1, visited)
				|| hasPathCore(matrix, rows, cols, row + 1, col, str, pathlength + 1, visited)) {
			return true;
		}
		//失败退回上一个
		visited[index] = false;
		return false;
	}

}