order
This article mainly records leetcode Whether the paths intersect
subject
Give you a string path, among path[i] The value of can be 'N'、'S'、'E' perhaps 'W', To the north 、 Southward 、 To the east 、 Move one unit West .
The robot starts from the origin on the two-dimensional plane (0, 0) Starting from , Press path The path indicated to walk .
If paths intersect at any point , That is to go to the position that has been passed before , Please return True ; otherwise , return False .
source ： Power button （LeetCode）
link ：https://leetcode-cn.com/problems/path-crossing
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .Answer key
class Solution {
public boolean isPathCrossing(String path) {
int x = 0;
int y = 0;
Set<String> pathSet = new HashSet<String>();
pathSet.add("00");
for (char c : path.toCharArray()) {
if (c == 'N') {
y++;
} else if (c == 'S') {
y--;
} else if (c == 'W') {
x--;
} else if (c == 'E') {
x++;
}
String p = String.valueOf(x) + String.valueOf(y);
if (pathSet.contains(p)) {
return true;
}
pathSet.add(p);
}
return false;
}
}Summary
Here to maintain the past point , Then traverse path The characters of , Yes x,y The coordinates move accordingly , After each move, judge whether the point has passed , Walk past and return true, If not, record the change points in the past points , After traversing, it will return if it does not meet the conditions false.
