intial commit number systems

Author: varun93

tuts/number-systems/README.md

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+## Number System
+
+Every software engineer should know these conversions.
+
+#TODO:
+
+Yet to handle decimal digits.

tuts/number-systems/binary-to-decimal.js

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+//using reduce
+const solution = binary => {
+  return binary.split("").reduce((result, bit, index) => {
+    return (
+      result + parseInt(binary[binary.length - index - 1]) * Math.pow(2, index)
+    );
+  }, 0);
+};
+
+const usingForLoops = binary => {
+  let result = 0,
+    power = 1;
+
+  for (let index = binary.length - 1; index >= 0; index--) {
+    if (binary[index] === "1") {
+      result += power * binary[index];
+    }
+    power *= 2;
+  }
+  return result;
+};
+
+console.log(usingForLoops("101"));

tuts/number-systems/binary-to-hex.js

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+const getHex = group => {
+  const mapping = {};
+  mapping["0000"] = "0";
+  mapping["0001"] = "1";
+  mapping["0010"] = "2";
+  mapping["0011"] = "3";
+  mapping["0100"] = "4";
+  mapping["0101"] = "5";
+  mapping["0110"] = "6";
+  mapping["0111"] = "7";
+  mapping["1000"] = "8";
+  mapping["1001"] = "9";
+  mapping["1010"] = "A";
+  mapping["1011"] = "B";
+  mapping["1100"] = "C";
+  mapping["1101"] = "D";
+  mapping["1110"] = "E";
+  mapping["1111"] = "F";
+  return mapping[group];
+};
+const solution = binary => {
+  let result = [];
+  const length = binary.length;
+  const extra = length % 4;
+  for (let i = length; i > extra; i -= 4) {
+    result.unshift(getHex(binary.slice(i - 4, i)));
+  }
+
+  result.unshift(
+    getHex(new Array(4 - extra).fill("0").join("") + binary.slice(0, extra))
+  );
+
+  return result.join("");
+};

tuts/number-systems/decimal-to-binary.js

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+const solution = decimal => {
+  if (decimal < 2) {
+    return decimal + "";
+  }
+  return solution(Math.floor(decimal / 2)) + (decimal % 2);
+};
+
+console.log(solution(1));

tuts/number-systems/decimal-to-hex.js

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+//can have a mapping instead of this
+const getHex = digit => {
+  digit = parseInt(digit);
+  if (digit > 9) {
+    return String.fromCharCode(55 + digit);
+  }
+  return digit + "";
+};
+
+const solution = decimal => {
+  if (decimal < 16) {
+    return getHex(decimal);
+  }
+  return solution(Math.floor(decimal / 16)) + getHex(decimal % 2);
+};
+
+console.log(solution(160));

tuts/number-systems/hex-to-binary.js

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+const getBinary = group => {
+  const mapping = {};
+  mapping["0"] = "0000";
+  mapping["1"] = "0001";
+  mapping["2"] = "0010";
+  mapping["3"] = "0011";
+  mapping["4"] = "0100";
+  mapping["5"] = "0101";
+  mapping["6"] = "0110";
+  mapping["7"] = "0111";
+  mapping["8"] = "1000";
+  mapping["9"] = "1001";
+  mapping["A"] = "1010";
+  mapping["B"] = "1011";
+  mapping["C"] = "1100";
+  mapping["D"] = "1101";
+  mapping["E"] = "1110";
+  mapping["F"] = "1111";
+  return mapping[group];
+};
+
+const solution = hex => {
+  return hex
+    .split("")
+    .map(digit => {
+      return getBinary(digit);
+    })
+    .join("");
+};

tuts/number-systems/hex-to-decimal.js

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+let convertHex = digit => {
+  return mapping[digit];
+};
+//using reduce
+const solution = hex => {
+  return hex.split("").reduce((result, bit, index) => {
+    return (
+      result + convertHex(hex[hex.length - index - 1]) * Math.pow(16, index)
+    );
+  }, 0);
+};
+
+const usingForLoops = hex => {
+  let result = 0,
+    power = 1;
+
+  for (let index = hex.length - 1; index >= 0; index--) {
+    result += power * convertHex(hex[index]);
+    power *= 16;
+  }
+  return result;
+};
+const mapping = {};
+mapping["0"] = 0;
+mapping["1"] = 1;
+mapping["2"] = 2;
+mapping["3"] = 3;
+mapping["4"] = 4;
+mapping["5"] = 5;
+mapping["6"] = 6;
+mapping["7"] = 7;
+mapping["8"] = 8;
+mapping["9"] = 9;
+mapping["A"] = 10;
+mapping["B"] = 11;
+mapping["C"] = 12;
+mapping["D"] = 13;
+mapping["E"] = 14;
+mapping["F"] = 15;
+
+console.log(solution("A0"));