数组排序

一

            NSMutableArray *numbers = [NSMutableArray arrayWithObjects:@3, @1, @4, @1, @5, @9, @2, @6, @5, @3, @5, nil];
            
            // 使用选项进行排序，这里我们不使用任何额外选项
            NSMutableArray *sortedNumbers = [numbers sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
                if ([obj1 integerValue] > [obj2 integerValue]) {
                    return NSOrderedDescending;
                } else if ([obj1 integerValue] < [obj2 integerValue]) {
                    return NSOrderedAscending;
                } else {
                    return NSOrderedSame;
                }
            }];
            

二

- (void)onononon
{
    NSMutableArray *array = [NSMutableArray arrayWithObjects:@3,@2,@9,@1,@6,@7,@4,@5,@8,@5,nil];
    [self quickSortArray:array withLeftIndex:0 andRightIndex:(int)array.count - 1];
    NSLog(@"排序后的数组===%@",array);
    
}

 
//快速排序
- (void)quickSortArray:(NSMutableArray *)array withLeftIndex:(NSInteger)leftIndex andRightIndex:(NSInteger)rightIndex{
    if (leftIndex >= rightIndex) {//如果数组长度为0或1时返回
        return ;
    }
    NSInteger i = leftIndex;
    NSInteger j = rightIndex;
    //记录比较基准数
    NSInteger key = [array[i] integerValue];
    while (i < j) {
        /**** 首先从右边j开始查找比基准数小的值 ***/
        while (i < j && [array[j] integerValue] >= key) {//如果比基准数大，继续查找
            j--;
        }
        //如果比基准数小，则将查找到的小值调换到i的位置
        array[i] = array[j];
        /**** 当在右边查找到一个比基准数小的值时，就从i开始往后找比基准数大的值 ***/
        while (i < j && [array[i] integerValue] <= key) {//如果比基准数小，继续查找
            i++;
        }
        //如果比基准数大，则将查找到的大值调换到j的位置
        array[j] = array[i];
    }
    //将基准数放到正确位置
    array[i] = @(key);
    /**** 递归排序 ***/
    //排序基准数左边的
    [self quickSortArray:array withLeftIndex:leftIndex andRightIndex:i - 1];
    //排序基准数右边的
    [self quickSortArray:array withLeftIndex:i + 1 andRightIndex:rightIndex];
}

    NSArray * array = @[@"20",@"80",@"99",@"86",@"68",@"39",@"69",@"23",@"79",@"97"];
    
    float sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
    
    float avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
    
    float max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
    
    float min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];