快速排序,冒泡排序,选择排序

- (void)viewDidLoad {
    [super viewDidLoad];
     
    NSMutableArray *array = [NSMutableArray array];
     
    //int x = arc4random() % 100;---- 表示 [0, 100)
    static int num = 100;
    for (int i = 0;i < num; i++) {
        u_int32_t x = arc4random() % num;
        NSNumber *num = [[NSNumber alloc] initWithInt:x];
        [array addObject:num];
    }
     
    [self sort:array left:0 right:array.count - 1];
    NSLog(@"%@",array);
}

- (void)sort:(NSMutableArray *)arr left:(NSInteger)left right:(NSInteger)right {
    if (left >= right) {
        return;
    }
    NSInteger i = left;
    NSInteger j = right;
<strong>    NSInteger point = [arr[left] integerValue];  // 取最左边的元素</strong>
    while(i != j){
        while (i < j && point <= [arr[j] integerValue]) {
            j --;
        }
        while (i < j && point >= [arr[i] integerValue]) {
            i ++;
        }
        if (i < j) {
            [arr exchangeObjectAtIndex:i withObjectAtIndex:j];
        }
    }
    [arr exchangeObjectAtIndex:i withObjectAtIndex:left]; // i++变化了
    [self sort:arr left:left right:i - 1];
    [self sort:arr left:i + 1 right:right];
}

步骤

参数：可变数组，left0,right count-1
i = left j = right point = arr[left]
while （i != j）

while(i<j && point <=arr[j])

j—

while(i<j && point >= arr[i])

if i<j

arr exchange i,j

arr exchange i left
self 调用这个方法 left i+1 right :right
self 调用这个方法 left left right：i-1
if(left >=right)return
参考
http://developer.51cto.com/art/201403/430986.htm
参考
http://www.jianshu.com/p/bfa34c56ffaa

冒泡排序和选择排序:

冒泡:

- (void)bubleSort:(NSMutableArray *)arr{ // j j 比较
    for (int i = 0; i < arr.count; i ++) {
        for (int j = 0; j < arr.count - 1; j++) {
            if (arr[j] >= arr[j+1]) {
                [arr exchangeObjectAtIndex:j withObjectAtIndex:j+1];
            }
        }
    }
    NSLog(@"冒泡排序-%@",arr);
}

选择:

- (void)selectSort:(NSMutableArray *)arr { // i j比较
    for (int i = 0 ; i < arr.count; i ++) {
        for (int j = i+1; j < arr.count; j++) {
            NSInteger temp = [arr[i] integerValue];
            if (arr[i] >= arr[j]) {
                arr[i] = arr[j];
                arr[j] = [NSNumber numberWithInteger:temp];
            }
        }
    }
    NSLog(@"选择排序-%@",arr);
}