first commit

src/brackets/index.js

@@ -4,6 +4,26 @@
  * @param {string} str The string of brackets.
  * @returns {"valid" | "invalid"} Whether or not the string is valid.
  */
-function isValid(str) {}
+function isValid(str) {
+  let bracket = [];
+  let opening = "({[";
+  let closing = ")}]";
+  let matching = {")":"(", "]":"[","}":"{" } ; 
+
+  for(let i= 0; i< str.length; i++) {
+    if(opening.includes(str[i])){
+        bracket.push(str[i])
+    } else if(closing.includes(str[i])) {
+        let lastBracket= bracket.pop();
+        if(matching[str[i]] !== lastBracket) { 
+            return "invalid"
+        }
+    }
+  }
+
+  return bracket.length === 0 ? "valid" : "invalid";
+};
+
+
 
 module.exports = isValid;

src/roman-numerals/index.js

@@ -4,6 +4,23 @@
  * @param {string} roman The all-caps Roman numeral between 1 and 3999 (inclusive).
  * @returns {number} The decimal equivalent.
  */
-function romanToDecimal(roman) {}
+
+function romanToDecimal(roman) {
+    let numeral= {I : 1, V : 5, X : 10, L : 50, C : 100, D : 500, M : 1000}
+    let result = 0
+    for(let i=0; i<roman.length; i++){
+    let currLetter = numeral[roman[i]];
+    let nextLetter = numeral[roman[i + 1]];
+    if(nextLetter && nextLetter> currLetter) {
+        result += nextLetter - currLetter 
+     i++    
+    } else {
+
+        result+= currLetter
+    }
+    }
+    return result
+};
+
 
 module.exports = romanToDecimal;

src/transpose/index.js

@@ -4,6 +4,9 @@
  * @param {number[]} array The array to transpose
  * @returns {number[]} The transposed array
  */
-function transpose(array) {}
+function transpose(array) {
+    return array[0].map((item, index)=> array.map( row =>row[index]));
+
+};
 
 module.exports = transpose;