常见的10种排序算法

￡神魔★判官ぃ 2023-09-28 17:13 120阅读 0赞

## 常见的10种排序算法 ##

**各排序算法的模板如下：**

1.  插入排序

void insert_sort()
    {
        for (int i = 1; i < n; i ++ )
        {
            int x = a[i];
            int j = i-1;
    
            while (j >= 0 && x < a[j])
            {
                a[j+1] = a[j];
                j -- ;
            }
            a[j+1] = x;
        }
    }

1.  选择排序

void select_sort()
    {
        for (int i = 0; i < n; i ++ )
        {
            int k = i;
            for (int j = i+1; j < n; j ++ )
            {
                if (a[j] < a[k])
                    k = j;
            }
            swap(a[i], a[k]);
        }
    
    }

1.  冒泡排序

void bubble_sort()
    {
        for (int i = n-1; i >= 1; i -- )
        {
            bool flag = true;
            for (int j = 1; j <= i; j ++ )
                if (a[j-1] > a[j])
                {
                    swap(a[j-1], a[j]);
                    flag = false;
                }
            if (flag) return;
        }
    }

1.  希尔排序

void shell_sort()
    {
        for (int gap = n >> 1; gap; gap >>= 1)
        {
            for (int i = gap; i < n; i ++ )
            {
                int x = a[i];
                int j;
                for (j = i; j >= gap && a[j-gap] > x; j -= gap)
                    a[j] = a[j-gap];
                a[j] = x;
            }
        }
    }

1.  快速排序（最快）

void quick_sort(int l, int r)
    {
        if (l >= r) return ;
    
        int x = a[l+r>>1], i = l-1, j = r+1;
        while (i < j)
        {
            while (a[++ i] < x);
            while (a[-- j] > x);
            if (i < j) swap(a[i], a[j]);
        }
        sort(l, j), sort(j+1, r);
    }

1.  归并排序

void merge_sort(int l, int r)
    {
        if (l >= r) return;
        int temp[N];
        int mid = l+r>>1;
        merge_sort(l, mid), merge_sort(mid+1, r);
        int k = 0, i = l, j = mid+1;
        while (i <= mid && j <= r)
        {
            if (a[i] < a[j]) temp[k ++ ] = a[i ++ ];
            else temp[k ++ ] = a[j ++ ];
    
        }
        while (i <= mid) temp[k ++ ] = a[i ++ ];
        while (j <= r) temp[k ++ ] = a[j ++ ];
        for (int i = l, j = 0; i <= r; i ++ , j ++ ) a[i] = temp[j];
    }

1.  堆排序

void down(int u)
    {
        int t = u;
        if (u<<1 <= n && h[u<<1] < h[t]) t = u<<1;
        if ((u<<1|1) <= n && h[u<<1|1] < h[t]) t = u<<1|1;
        if (u != t)
        {
            swap(h[u], h[t]);
            down(t);
        }
    }
    
    int main()
    {
        for (int i = 1; i <= n; i ++ ) cin >> h[i];
        for (int i = n/2; i; i -- ) down(i);
        while (true)
        {
            if (!n) break;
            cout << h[1] << ' ';
            h[1] = h[n];
            n -- ;
            down(1);
        }
        return 0;
    }

1.  基数排序

int maxbit()
    {
        int maxv = a[0];
        for (int i = 1; i < n; i ++ )
            if (maxv < a[i])
                maxv = a[i];
        int cnt = 1;
        while (maxv >= 10) maxv /= 10, cnt ++ ;
    
        return cnt;
    }
    void radixsort()
    {
        int t = maxbit();
        int radix = 1;
    
        for (int i = 1; i <= t; i ++ )
        {
            for (int j = 0; j < 10; j ++ ) count[j] = 0;
            for (int j = 0; j < n; j ++ )
            {
                int k = (a[j] / radix) % 10;
                count[k] ++ ;
            }
            for (int j = 1; j < 10; j ++ ) count[j] += count[j-1];
            for (int j = n-1; j >= 0; j -- )
            {
                int k = (a[j] / radix) % 10;
                temp[count[k]-1] = a[j];
                count[k] -- ;
            }
            for (int j = 0; j < n; j ++ ) a[j] = temp[j];
            radix *= 10;
        }
    
    }

1.  计数排序

void counting_sort()
    {
        int sorted[N];
        int maxv = a[0];
        for (int i = 1; i < n; i ++ )
            if (maxv < a[i])
                maxv = a[i];
        int count[maxv+1];
        for (int i = 0; i < n; i ++ ) count[a[i]] ++ ;
        for (int i = 1; i <= maxv; i ++ ) count[i] += count[i-1];
        for (int i = n-1; i >= 0; i -- )
        {
            sorted[count[a[i]]-1] = a[i];
            count[a[i]] -- ;
        }
        for (int i = 0; i < n; i ++ ) a[i] = sorted[i];
    }

1.  桶排序

vector<int> bucketSort(vector<int>& nums) {
        int n = nums.size();
        int maxv = *max_element(nums.begin(), nums.end());
        int minv = *min_element(nums.begin(), nums.end());
        int bs = 1000;
        int m = (maxv-minv)/bs+1;
        vector<vector<int> > bucket(m);
        for (int i = 0; i < n; ++i) {
            bucket[(nums[i]-minv)/bs].push_back(nums[i]);
        }
        int idx = 0;
        for (int i = 0; i < m; ++i) {
            int sz = bucket[i].size();
            bucket[i] = quickSort(bucket[i]);
            for (int j = 0; j < sz; ++j) {
                nums[idx++] = bucket[i][j];
            }
        }
        return nums;
    }

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