my mini-challenge

src/brackets/index.js

@@ -4,6 +4,27 @@
  * @param {string} str The string of brackets.
  * @returns {"valid" | "invalid"} Whether or not the string is valid.
  */
-function isValid(str) {}
+function isValid(str) {
+    let arrBracket = [];
+
+    for (let i in str) {
+        if (str[i] == '(' || str[i] == '[' || str[i] == '{') {
+            arrBracket.push(str[i]);
+        } else {
+            let braInd = arrBracket.length - 1;
+
+            if (str[i] == ')' && arrBracket[braInd] == '(') {
+                arrBracket.pop();
+            } else if (str[i] == ']' && arrBracket[braInd] == '[') {
+                arrBracket.pop();
+            } else if (str[i] == '}' && arrBracket[braInd] == '{') {
+                arrBracket.pop();
+            } else {
+                return 'invalid';
+            }
+        }
+    }
+    return arrBracket.length == 0 ? 'valid' : 'invalid';
+}
 
 module.exports = isValid;

src/roman-numerals/index.js

@@ -4,6 +4,29 @@
  * @param {string} roman The all-caps Roman numeral between 1 and 3999 (inclusive).
  * @returns {number} The decimal equivalent.
  */
-function romanToDecimal(roman) {}
+function romanToDecimal(roman) {
+    const values = {
+        I : 1,
+        V : 5,
+        X : 10,
+        L : 50,
+        C : 100,
+        D : 500,
+        M : 1000,
+    }
+    let result = 0;
+    let previousChar = 0;
+    for (let i = roman.length -1; i >= 0; i--){
+        const currentChar = values[roman[i]];
+        if (currentChar < previousChar){
+            result -= currentChar;
+        } else {
+            result += currentChar;
+        }
+        previousChar = currentChar
+    }
+    return result
 
+}
+
 module.exports = romanToDecimal;

src/transpose/index.js

@@ -4,6 +4,15 @@
  * @param {number[]} array The array to transpose
  * @returns {number[]} The transposed array
  */
-function transpose(array) {}
+function transpose(array) {
+    let transposedArr = [];
+    for (let i=0; i < array[0].length; i++){
+    transposedArr[i] = [];
+        for (let j=0; j < array.length; j++){
+            transposedArr[i][j] = array[j][i]
+        }
+    }
+return transposedArr     
+}
 
 module.exports = transpose;