选择排序

选择排序工作原理是每一次从待排序的数据元素中选出最小（或最大）的一个元素，存放在序列的起始位置，直到全部待排序的数据元素排完。这里依旧分别列出C、OC和swift版本的代码，欢迎交流、指正。

C语言版

//函数声明
void select_sort(int a[], int n);

int array[11] = {23, 8, 90, 12, 7, -9, 54, 3, 36, 99, -17};
//调用
select_sort(array, 11);
printf("sort result:");
for (int p = 0; p < 11; p++) {
    printf(" %d", array[p]);
}
printf("
");
//sort result: -17 -9 3 7 8 12 23 36 54 90 99

void select_sort(int a[], int n) {
    int min = 0;
    //每次找到第（i+1）小的数 从左到右依次排列
    for (int i = 0; i < n-1; i++) {
        min = i;
        //找到第（i+1）小的数的下标
        for (int j = i+1; j < n; j++) {
            if (a[j] < a[min]) {
                min = j;
            }
        }
        
        int temp = a[i];
        a[i]     = a[min];
        a[min]   = temp;
    }
}

OC版

_dataArray = [NSMutableArray arrayWithObjects:@21, @3, @34, @(-28), @10, @(-33), @54, @9, @0, @(-2),  nil];

[self selectSort];
NSString *string = [self.dataArray componentsJoinedByString:@" "];
NSLog(@"sort result : %@", string);
//sort result : -33 -28 -2 0 3 9 10 21 34 54

- (void)selectSort {
    NSInteger minIndex = 0;
    for (int i = 0; i < self.dataArray.count-1; i++) {
        minIndex = i;
        for (int j = i+1; j < self.dataArray.count; j++) {
            if ([self.dataArray[j] integerValue] < [self.dataArray[minIndex] integerValue]) {
                minIndex = j;
            }
        }
        
        [self.dataArray exchangeObjectAtIndex:i withObjectAtIndex:minIndex];
    }
}

swift版

var dataArray:NSMutableArray = [76, 1, 19, -4, 2, 4, 6, 8, 0, -19];

self.selectSort();
let string:NSString = dataArray.componentsJoinedByString(" ");
NSLog("sort result: %@", string);
//sort result: -19 -4 0 1 2 4 6 8 19 76

func selectSort() {
    var minIndex:NSInteger = 0;
    
    for i:NSInteger in 0..<dataArray.count-1 {
        minIndex = i;
        for j:NSInteger in i+1..<dataArray.count {
            if dataArray[j].integerValue < dataArray[minIndex].integerValue {
                minIndex = j;
            }
        }
        
        dataArray.exchangeObjectAtIndex(i, withObjectAtIndex:minIndex);
    }
}