1138. Alphabet Board Path.md

1138. Alphabet Board Path

Solution

• represent the entire alphebat as array and get y x by index/5 and index%5
• corner case of z: when we change one character to z, make sure ‘L’ first and 'D'

class Solution {
    //corner case: z
    public String alphabetBoardPath(String target) {
        String str  ="abcdefghijklmnopqrstuvwxyz";
        StringBuilder sb = new StringBuilder();
        int y = 0, x = 0;
        for(int i= 0; i<target.length(); i++){
            char c = target.charAt(i);
            int index = str.indexOf(c);
            int ty = index/5;
            int tx = index%5;
            
            //add uplr into sb
            int yDiff = ty-y;
            int xDiff = tx-x;
            if(c=='z' && i!=0){
                //5 0 
                //0 3
                //System.out.println(ty+" "+tx);
                //System.out.println("l"+i);
                if(xDiff>0){
                    while(xDiff>0){
                        sb.append('R');
                        xDiff--;
                    }
                }else{
                    xDiff = -xDiff;
                    while(xDiff>0){
                        sb.append('L');
                        xDiff--;
                    }
                }   
                if(yDiff>0){
                while(yDiff>0){
                    sb.append('D');
                    yDiff--;
                    }
                }else{
                    yDiff = -yDiff;
                    while(yDiff>0){
                        sb.append('U');
                        yDiff--;
                    }
                }
                
            }else {
                if(yDiff>0){
                while(yDiff>0){
                    sb.append('D');
                    yDiff--;
                    }
                }else{
                    yDiff = -yDiff;
                    while(yDiff>0){
                        sb.append('U');
                        yDiff--;
                    }
                }
                if(xDiff>0){
                    while(xDiff>0){
                        sb.append('R');
                        xDiff--;
                    }
                }else{
                    xDiff = -xDiff;
                    while(xDiff>0){
                        sb.append('L');
                        xDiff--;
                    }
                }
            }
            
            
            sb.append('!');
            
            y  =ty;
            x = tx;
        }
            
            
        return sb.toString();
    }
}

Solution 2

• move x and y, when x==4 && y>0 breaj since it hits z