情况：

SVN更新多次之后会出现错误：

Server sent unexpected return value (403 Forbidden) in response to OPTIONS

解决：

使用switch 重新定位svn路径

小例实现步骤：

①.在MainActivity里面发送两种类型的广播：sendBroadcast和sendStickyBroacat。

②在ReceverActivity里面通过BroadcastReceiver来接收这两个消息，这里是通过代码来注册Recevier而不是在Manifest里面注册的。

③结论：通过sendBroadcast中发出的intent在ReceverActivity不处于onResume状态是无法接受到的，即使后面再次使其处于该状态也无法接受到。而sendStickyBroadcast发出的Intent当ReceverActivity重新处于onResume状态之后就能重新接受到其Intent。这就是the Intent will be held to be re-broadcast to future receivers这句话的表现。就是说sendStickyBroadcast发出的最后一个Intent会被保留，下次当Recevier处于活跃的时候，又会接受到它。

④在wifi中就是发送的粘性广播。

下面是两个类的代码部分。

MainActivity：

public class MainActivity extends Activity {   
    Button btnSendi;   
    Button btnSends;   
    Button btnStart;   
    Context mContext;   
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {   
        super.onCreate(savedInstanceState);   
        setContentView(R.layout.main);   
        btnSendi=(Button) findViewById(R.id.sendi);   
        btnSends=(Button) findViewById(R.id.sends);   
        btnStart=(Button) findViewById(R.id.start);   
        mContext=getApplicationContext();   
        btnSendi.setOnClickListener(new OnClickListener(){   
  
            @Override  
            public void onClick(View v) {   
                // TODO Auto-generated method stub   
                Intent intent = new Intent();   
                intent.setAction("com.android.my.action");   
                intent.setFlags(1);   
                mContext.sendBroadcast(intent);   
            }   
               
        });   
           
        btnStart.setOnClickListener(new OnClickListener(){   
  
            @Override  
            public void onClick(View v) {   
                // TODO Auto-generated method stub   
                Intent intent = new Intent(MainActivity.this,ReceiverActivity.class);   
                  
                startActivity(intent);   
            }   
               
        });   
           
        btnSends.setOnClickListener(new OnClickListener(){   
  
            @Override  
            public void onClick(View v) {   
                // TODO Auto-generated method stub   
                Intent intent = new Intent();   
                intent.setAction("com.android.my.action.sticky");   
                intent.setFlags(2);   
                mContext.sendStickyBroadcast(intent);   
            }   
               
        });   
    }   
}  

ReceiverActivity ：

public class ReceiverActivity extends Activity {   
     private IntentFilter mIntentFilter;   
       
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {   
        super.onCreate(savedInstanceState);   
        setContentView(R.layout.main);   
        mIntentFilter = new IntentFilter();   
        mIntentFilter.addAction("com.android.my.action");   
        mIntentFilter.addAction("com.android.my.action.sticky");   
  
               
    }   
    private BroadcastReceiver mReceiver = new BroadcastReceiver() {   
  
        @Override  
        public void onReceive(Context context, Intent intent) {   
            final String action = intent.getAction();   
            System.out.println("action"+action);   
               
        }   
    };   
       
    @Override  
    protected void onResume() {   
        // TODO Auto-generated method stub   
        super.onResume();   
        registerReceiver(mReceiver, mIntentFilter);   
    }   
       
    @Override  
    protected void onPause() {   
        // TODO Auto-generated method stub   
        super.onPause();   
        unregisterReceiver(mReceiver);   
    }   
       
       
}  

      原本以为精度问题，原来是最后需要一个换行。直接暴力是0.216，如果加个弱弱的排序优化一下是0.120。

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>

#define sqr(x) ((x)*(x))

typedef struct _Point {
    double x, y, z;
}Point;

int cmp(const void *_a, const void *_b) {
    Point* a = (Point *)_a;
    Point* b = (Point *)_b;

    return (int)(a->x - b->x);
}

int main() {
    Point p[5005];
    int n = 0, r[15];
    double x, y, z;

    while (scanf("%lf%lf%lf", &x, &y, &z)) {
        if (x+y+z < 1e-9)   break;
        p[n].x = x;
        p[n].y = y;
        p[n].z = z;
        n++;
    }

    qsort(p, n, sizeof (p[0]), cmp);

    memset(r, 0, sizeof (r));

    for (int i=0; i<n; i++) {
        int tmin = 10;

        for (int j=0; j<n; j++) {
            if (i == j) continue;

            if (p[j].x-p[i].x > 10) // 如果x上距离超过了10不再搜索
                break;

            int tmp = (int)(sqrt(sqr(p[i].x-p[j].x) + sqr(p[i].y-p[j].y)
                                + sqr(p[i].z-p[j].z)));
            tmin = tmin < tmp ? tmin : tmp;
        }

        r[tmin]++;
    }

    for (int i=0; i<10; i++)
        printf("%4d", r[i]);
    printf("\n");
    return 0;
}