```
public class Solution {
public boolean isSelfCrossing(int[] x) {
if(x.length < 4) return false;
int i = 0, base = 0;
while(i+4 <= x.length){
if(x[i] - x[i+2] >= 0 && x[i+1] - x[i+3] <= base) return true;
else if(x[i+1] - x[i+3] > base) base = 0;
else base = x[i];
i++;
}
return false;
}
}
```