java算法面试题积累

public static int str2Int(){
	byte[] strb="123456".getBytes(); // getBytes()
	int result=0;
	for(int i=0;i<strb.length;i++){
		//System.out.println(strb[i]);
		if(strb[i]>'0'&&strb[i]<'9'){
			int ival=strb[i]-'0';
			//System.out.println(ival);
			result=result*10+ival;
		}
	}
	System.out.println(result);
	return result;
}


public static int str2Int2(){
	char[] strb="123456".toCharArray();// toCharArray()
	int result=0;
	for(int i=0;i<strb.length;i++){
		//System.out.println(strb[i]);
		if(strb[i]>'0'&&strb[i]<'9'){
			int ival=strb[i]-'0';
			//System.out.println(ival);
			result=result*10+ival;
		}
	}
	System.out.println(result);
	return result;
}


public static void sort(){
	int a[]={1,54,6,3,78,34,12,45};
	int temp=0;
	for(int i=0;i<a.length;i++){
		for(int j=i+1;j<a.length;j++){
			if(a[i]>a[j]){//
				temp=a[i];
				a[i]=a[j];
				a[j]=temp;
			}
		}
		for(int t:a){
			System.out.print(t+"\t");
		}
		System.out.println();
	}
	for(int t:a){
		System.out.print(t+"\t");
	}
}


public static void buddleSort(){
	int a[]={1,54,6,3,78,34,12,45};
	int temp=0;
	for(int i=0;i<a.length;i++){
		for(int j=0;j<a.length-i-1;j++){
			if(a[j]>a[j+1]){//
				temp=a[j];
				a[j]=a[j+1];
				a[j+1]=temp;
			}
		}
		for(int t:a){
			System.out.print(t+"\t");
		}
		System.out.println();
	}
	for(int t:a){
		System.out.print(t+"\t");
	}
}


public static void max(){
	String str=String.valueOf(Long.MAX_VALUE);
	System.out.println(str);
	int[] n=new int[str.length()+1];
	byte[] b=str.getBytes();
	int p=0;
	for(int i=b.length-1;i>=0;i--){
		int m=(b[i]-'0')*2+p;
		if(m>9){
			n[i+1]=m%10;
			p=m/10;
		}else{
			n[i+1]=m;
			p=0;
		}
	}
	if(p>0){
		n[0]=p;
	}
	for(int i=0;i<n.length;i++){
		System.out.print(n[i]);
	}
}