63 lines
2.0 KiB
C#
63 lines
2.0 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace my_leetcode
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{
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internal class Solution
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{
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/// <summary>
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/// 268.丢失的数字
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/// </summary>
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/// <param name="nums">数组</param>
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/// <returns>丢失的数字</returns>
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public int MissingNumber(int[] nums)
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{
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return new int[4] { nums.Length, 1, nums.Length + 1, 0 }[nums.Length & 3] ^ nums.Aggregate(0, (o, n) => o ^ n);
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}
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/// <summary>
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/// 69.Sqrt(x)
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/// </summary>
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/// <param name="x">x</param>
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/// <returns>平方根</returns>
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public int MySqrt(int x)
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{
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double xHalf = 0.5 * x;
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long i = BitConverter.DoubleToInt64Bits(x);
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i = 0x1FF7A3BEA91D9B1B + (i >> 1);
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double f = BitConverter.Int64BitsToDouble(i);
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f = f * 0.5 + xHalf / f;
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f = f * 0.5 + xHalf / f;
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f = f * 0.5 + xHalf / f;
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return (int)f;
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}
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/// <summary>
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/// 640. 求解方程
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/// </summary>
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/// <param name="equation">方程式</param>
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/// <returns>解</returns>
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public string SolveEquation(string equation)
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{
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var (a, b, c, sign, left, hasC) = (0, 0, 0, 1, 1, false);
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foreach (var z in equation)
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{
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(a, b, c, sign, left, hasC) = z switch
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{
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'x' => (a + (hasC ? sign * left * c : sign * left), b, 0, sign, left, false),
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'+' => (a, b + sign * left * c, 0, 1, left, false),
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'-' => (a, b + sign * left * c, 0, -1, left, false),
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'=' => (a, b + sign * left * c, 0, 1, -1, false),
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_ => (a, b, c * 10 + z - '0', sign, left, true)
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};
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}
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b += sign * left * c;
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return a == 0 ? b == 0 ? "Infinite solutions" : "No solution" : "x=" + -b / a;
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}
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}
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}
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