求兩點的距離
CGFloat GetPointDistance (CGPoint p0, CGPoint p1)
{
CGFloat xDiff = p0.x - p1.x;
CGFloat yDiff = p0.y - p1.y;
return sqrtf ((xDiff * xDiff) + (yDiff * yDiff));
}
使用權重控制隨機選取
水果 | Apple | Orange | Banana | Mango ------------------------------------------ 權重 | 70 | 10 | 10 | 10 從這個表中，我們分派了各個權重，我們希望Apple最常被抽中，所以將權重設定較高的值。 因此我們從這個表來實現作法。 fruits = [[NSArray alloc] initWithObjects:@"apple",@"orange",@"banana",@"mango", nil]; //定義水果 weights = [[NSArray alloc] initWithObjects:[NSNumber numberWithInt:70],[NSNumber numberWithInt:10],[NSNumber numberWithInt:10],[NSNumber numberWithInt:10], nil]; //定義權重 int currentfruit=0; NSMutableArray *weighedfruits = [[NSMutableArray alloc] init]; while (currentfruit<[fruits count]){ //step through each fruit[] element for (int i = 0; i < [[weights objectAtIndex:currentfruit] intValue]; i++) { [weighedfruits addObject: [fruits objectAtIndex:currentfruit]]; ...
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