StarMirror/CS-Notes
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

auto commit

Browse Source
This commit is contained in:
CyC2018 2019-10-17 01:58:26 +08:00
parent 63b4122c46
commit cac408908f
2 changed files with 20 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
docs/notes/Leetcode 题解 - 搜索.md
View File

@ -61,6 +61,8 @@
## 1. 计算在网格中从原点到特定点的最短路径长度 ## 1. 计算在网格中从原点到特定点的最短路径长度
[1091. Shortest Path in Binary Matrix(Medium)](https://leetcode.com/problems/shortest-path-in-binary-matrix/)
```html ```html
[[1,1,0,1], [[1,1,0,1],
[1,0,1,0], [1,0,1,0],
@ -68,12 +70,12 @@
[1,0,1,1]] [1,0,1,1]]
``` ```
题目描述：1 表示可以经过某个位置，求解从 (0, 0) 位置到 (tr, tc) 位置的最短路径长度。 题目描述：0 表示可以经过某个位置，求解从左上角到右下角的最短路径长度。
```java ```java
public int minPathLength(int[][] grids, int tr, int tc) { public int shortestPathBinaryMatrix(int[][] grids) {
final int[][] direction = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}}; int[][] direction = {{1, -1}, {1, 0}, {1, 1}, {0, -1}, {0, 1}, {-1, -1}, {-1, 0}, {-1, 1}};
final int m = grids.length, n = grids[0].length; int m = grids.length, n = grids[0].length;
Queue<Pair<Integer, Integer>> queue = new LinkedList<>(); Queue<Pair<Integer, Integer>> queue = new LinkedList<>();
queue.add(new Pair<>(0, 0)); queue.add(new Pair<>(0, 0));
int pathLength = 0; int pathLength = 0;
@ -83,14 +85,14 @@ public int minPathLength(int[][] grids, int tr, int tc) {
while (size-- > 0) { while (size-- > 0) {
Pair<Integer, Integer> cur = queue.poll(); Pair<Integer, Integer> cur = queue.poll();
int cr = cur.getKey(), cc = cur.getValue(); int cr = cur.getKey(), cc = cur.getValue();
grids[cr][cc] = 0; // 标记 grids[cr][cc] = 1; // 标记
for (int[] d : direction) { for (int[] d : direction) {
int nr = cr + d[0], nc = cc + d[1]; int nr = cr + d[0], nc = cc + d[1];
if (nr < 0 || nr >= m || nc < 0 || nc >= n || grids[nr][nc] == 0) { if (nr < 0 || nr >= m || nc < 0 || nc >= n || grids[nr][nc] == 1) {
continue; continue;
} }
if (nr == tr && nc == tc) { if (nr == m - 1 && nc == n - 1) {
return pathLength; return pathLength + 1;
} }
queue.add(new Pair<>(nr, nc)); queue.add(new Pair<>(nr, nc));
} }

18
notes/Leetcode 题解 - 搜索.md
View File

@ -61,6 +61,8 @@
## 1. 计算在网格中从原点到特定点的最短路径长度 ## 1. 计算在网格中从原点到特定点的最短路径长度
[1091. Shortest Path in Binary Matrix(Medium)](https://leetcode.com/problems/shortest-path-in-binary-matrix/)
```html ```html
[[1,1,0,1], [[1,1,0,1],
[1,0,1,0], [1,0,1,0],
@ -68,12 +70,12 @@
[1,0,1,1]] [1,0,1,1]]
``` ```
题目描述：1 表示可以经过某个位置，求解从 (0, 0) 位置到 (tr, tc) 位置的最短路径长度。 题目描述：0 表示可以经过某个位置，求解从左上角到右下角的最短路径长度。
```java ```java
public int minPathLength(int[][] grids, int tr, int tc) { public int shortestPathBinaryMatrix(int[][] grids) {
final int[][] direction = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}}; int[][] direction = {{1, -1}, {1, 0}, {1, 1}, {0, -1}, {0, 1}, {-1, -1}, {-1, 0}, {-1, 1}};
final int m = grids.length, n = grids[0].length; int m = grids.length, n = grids[0].length;
Queue<Pair<Integer, Integer>> queue = new LinkedList<>(); Queue<Pair<Integer, Integer>> queue = new LinkedList<>();
queue.add(new Pair<>(0, 0)); queue.add(new Pair<>(0, 0));
int pathLength = 0; int pathLength = 0;
@ -83,14 +85,14 @@ public int minPathLength(int[][] grids, int tr, int tc) {
while (size-- > 0) { while (size-- > 0) {
Pair<Integer, Integer> cur = queue.poll(); Pair<Integer, Integer> cur = queue.poll();
int cr = cur.getKey(), cc = cur.getValue(); int cr = cur.getKey(), cc = cur.getValue();
grids[cr][cc] = 0; // 标记 grids[cr][cc] = 1; // 标记
for (int[] d : direction) { for (int[] d : direction) {
int nr = cr + d[0], nc = cc + d[1]; int nr = cr + d[0], nc = cc + d[1];
if (nr < 0 || nr >= m || nc < 0 || nc >= n || grids[nr][nc] == 0) { if (nr < 0 || nr >= m || nc < 0 || nc >= n || grids[nr][nc] == 1) {
continue; continue;
} }
if (nr == tr && nc == tc) { if (nr == m - 1 && nc == n - 1) {
return pathLength; return pathLength + 1;
} }
queue.add(new Pair<>(nr, nc)); queue.add(new Pair<>(nr, nc));
} }