计算机语言 – 第 3 页

[力扣] 算法 190 (C++)

190. 颠倒二进制位

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        auto ret = (n >> 16) | (n << 16);// ((ret & 0xffff0000) >> 16) | ((ret & 0x0000ffff) << 16)
        ret = ((ret & 0xff00ff00) >> 8) | ((ret & 0x00ff00ff) << 8);
        ret = ((ret & 0xf0f0f0f0) >> 4) | ((ret & 0x0f0f0f0f) << 4);// 1111 0000
        ret = ((ret & 0xcccccccc) >> 2) | ((ret & 0x33333333) << 2);// 1100 0011
        ret = ((ret & 0xaaaaaaaa) >> 1) | ((ret & 0x55555555) << 1);// 1010 0101
        return ret;
    }
};

[转载] OpenGL纹理倾斜扭曲问题

OpenGL纹理倾斜扭曲问题

调用以下函数：

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

[力扣] 算法 191 (C#)

191. 位1的个数

public class Solution
{
    public int HammingWeight(uint n)
    {
        var ret = 0;
        while(n != 0)
        {
            ret += (int)(n & 1);
            n >>= 1;
        }
        return ret;
    }
}

[力扣] 算法 1544 (C#)

1544. 整理字符串

public class Solution
{
    public string MakeGood(string s)
    {
        var deque = new LinkedList<char>();
        foreach(var ch in s)
            if (deque.Count != 0 && test(deque.Last.Value, ch))
                deque.RemoveLast();
            else
                deque.AddLast(ch);
        return string.Concat(deque);
    }

    public static bool test(char a ,char b)
    {
        if (a > 'Z')
            (a, b) = (b, a);
        return b - a == 'a' - 'A';
    }
}

[力扣] 算法 150 (C#)

150. 逆波兰表达式求值

public class Solution
{
    public int EvalRPN(string[] tokens)
    {
        var stack = new Stack<int>();
        foreach (var token in tokens)
        {
            switch (token)
            {
                case var add when add == "+":
                    stack.Push(stack.Pop() + stack.Pop());
                    break;
                case var minus when minus == "-":
                    stack.Push(-stack.Pop() + stack.Pop());
                    break;
                case var mul when mul == "*":
                    stack.Push(stack.Pop() * stack.Pop());
                    break;
                case var div when div == "/":
                    var top = stack.Pop();
                    stack.Push(stack.Pop() / top);
                    break;
                default:
                    stack.Push(int.Parse(token));
                    break;
            }
        }
        return stack.Pop();
    }
}

[力扣] 算法 1603 (C#)

1603. 设计停车系统

public class ParkingSystem
{
    readonly int[] remained;
    public ParkingSystem(int big, int medium, int small)
    {
        remained = new int[] { 0, big, medium, small };
    }

    public bool AddCar(int carType)
    {
        if (remained[carType] > 0)
        {
            remained[carType]--;
            return true;
        }
        return false;
    }
}

[力扣] 算法 59 (C#)

59. 螺旋矩阵 II

public class Solution {
    public int[][] GenerateMatrix(int n) {
        var ret = new int[n][];
        for (var i = 0; i < ret.Length; i++)
            ret[i] = new int[n];
        var loc = (x:0, y:0);
        var dir = (x:0, y:1);
        for(var i = 0; i < n * n; i++)
        {
            ret[loc.x][loc.y] = i + 1;
            var next = (x:loc.x + dir.x, y:loc.y + dir.y);
            if(next.x < 0 || next.y<0||next.x == n || next.y == n || ret[next.x][next.y] != 0)
            {
                dir = (dir.y, -dir.x);
                next = (x: loc.x + dir.x, y: loc.y + dir.y);
            }
            loc = next;
        }
        return ret;
    }
}

[力扣] 算法 331 (C#)

331. 验证二叉树的前序序列化

public class Solution {
    public bool IsValidSerialization(string preorder) {
        var arr = preorder.Split(',');
        if (arr.Length == 0)
            return true;
        if (arr.Length % 2 == 0)
            return false;
        var degree = 1;
        foreach (var ch in arr) {
            if (degree == 0)
                return false;
            degree += (ch == "#" ? -1 : +1);
        }
        return degree == 0;
    }
}

[力扣] 算法 227 (C#)

227. 基本计算器 II

直接拿 224 的代码改（尽管这道题不用处理括号）

public class Solution
{
    public int Calculate(string s) => Bar(Foo(s));

    List<IConvertible> Foo(string s)
    {
        var stack = new Stack<char>(s.Length);// ( + - * / only
        var ret = new List<IConvertible>(s.Length);
        for (var i = 0; i < s.Length; i++)
        {
            var ch = s[i];
            switch (ch)
            {
                case '(':
                    stack.Push('(');
                    break;
                case ')':
                    char top;
                    while ((top = stack.Pop()) != '(')
                        ret.Add(top);
                    break;
                case '+':
                case '-':
                    while (stack.Count > 0 && stack.Peek() != '(')
                        ret.Add(stack.Pop());
                    stack.Push(ch);
                    break;
                case '*':
                case '/':
                    while (stack.Count > 0 && (stack.Peek() == '*' || stack.Peek() == '/'))
                        ret.Add(stack.Pop());
                    stack.Push(ch);
                    break;
                case ' ':
                    break;
                default:// 0 ~ 9
                    long num = ch - '0';
                    for (; i + 1 < s.Length && s[i + 1] >= '0' && s[i + 1] <= '9'; i++)
                    {
                        num *= 10;
                        num += s[i + 1] - '0';
                    }
                    ret.Add(num);
                    break;
            }
        }
        while (stack.Count > 0)
            ret.Add(stack.Pop());
        return ret;
    }

    int Bar(List<IConvertible> foo)
    {
        var stack = new Stack<long>();
        foreach (var f in foo)
        {
            switch (f)
            {
                case '+':
                    stack.Push(stack.Pop() + stack.Pop());
                    break;
                case '-':
                    if (stack.Count > 1)
                        stack.Push(-(stack.Pop() - stack.Pop()));
                    else
                        stack.Push(-stack.Pop());
                    break;
                case '*':
                    stack.Push(stack.Pop() * stack.Pop());
                    break;
                case '/':
                    var got = stack.Pop();
                    stack.Push(stack.Pop() / got);
                    break;
                default:// long
                    stack.Push((long)f);
                    break;
            }
        }
        return (int)stack.Peek();
    }
}

[力扣] 算法 224 (C#)

224. 基本计算器

public class Solution
{
    public int Calculate(string s) => Bar(Foo(s));

    List<IConvertible> Foo(string s)
    {
        var stack = new Stack<char>(s.Length);// ( + - only
        var ret = new List<IConvertible>(s.Length);
        for (var i = 0; i < s.Length; i++)
        {
            var ch = s[i];
            switch (ch)
            {
                case '(':
                    stack.Push('(');
                    break;
                case ')':
                    char top;
                    while ((top = stack.Pop()) != '(')
                        ret.Add(top);
                    break;
                case '+':
                case '-':
                    while (stack.Count > 0 && stack.Peek() != '(')
                        ret.Add(stack.Pop());
                    stack.Push(ch);
                    break;
                case ' ':
                    break;
                default:// 0 ~ 9
                    long num = ch - '0';
                    for (; i + 1 < s.Length && s[i + 1] >= '0' && s[i + 1] <= '9'; i++)
                    {
                        num *= 10;
                        num += s[i + 1] - '0';
                    }
                    ret.Add(num);
                    break;
            }
        }
        while (stack.Count > 0)
            ret.Add(stack.Pop());
        return ret;
    }

    int Bar(List<IConvertible> foo)
    {
        var stack = new Stack<long>();
        foreach (var f in foo)
        {
            switch (f)
            {
                case '+':
                    stack.Push(stack.Pop() + stack.Pop());
                    break;
                case '-':
                    if (stack.Count > 1)
                        stack.Push(-(stack.Pop() - stack.Pop()));
                    else
                        stack.Push(-stack.Pop());
                    break;
                default:// long
                    stack.Push((long)f);
                    break;
            }
        }
        return (int)stack.Peek();
    }
}

参考资料

表达式树与前中后缀表达式

日	一	二	三	四	五	六
	1	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16	17	18	19	20
21	22	23	24	25	26	27
28	29	30