this is my first mini-challenge

src/brackets/index.js

@@ -4,6 +4,35 @@
  * @param {string} str The string of brackets.
  * @returns {"valid" | "invalid"} Whether or not the string is valid.
  */
-function isValid(str) {}
+
+function isValid(str) {
+    let stack = []
+    for(let i in str) {
+        let x = stack.length - 1
+        if(str[i]=="(" || str[i]=="{" || str[i]=="[") {
+            stack.push(str[i])
+        }
+        else{
+            if(str[i]== ")" && stack[x]=="(") {
+                stack.pop()
+            }
+            else if(str[i]=="}" && stack[x]=="{") {
+                stack.pop()
+            }
+            else if(str[i]=="]" && stack[x]=="[") {
+                stack.pop()
+            }
+            else{
+                return "invalid"
+            }
+        }
+    }
+    return stack.length > 0 ? "invalid" : "valid"
+}
 
 module.exports = isValid;
+
+
+
+
+

src/roman-numerals/index.js

@@ -4,6 +4,35 @@
  * @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 stack = [];
+  let total = 0;
+
+  const romanNumerals = {
+    I: 1,
+    V: 5,
+    X: 10,
+    L: 50,
+    C: 100,
+    D: 500,
+    M: 1000,
+  };
+
+  for (let i = 0; i < roman.length; i++) {
+    const currentSymbol = roman[i];
+    const currentValue = romanNumerals[currentSymbol];
+    const nextValue = romanNumerals[roman[i + 1]];
+
+    if (nextValue && currentValue < nextValue) {
+      total -= currentValue;
+    } else {
+      total += currentValue;
+    }
+  }
+
+  return total;
+}
+
 
 module.exports = romanToDecimal;

src/transpose/index.js

@@ -4,6 +4,23 @@
  * @param {number[]} array The array to transpose
  * @returns {number[]} The transposed array
  */
-function transpose(array) {}
 
-module.exports = transpose;
+function transpose(array) {
+    const numRows = array.length;
+    const numCols = array[0].length;
+
+    const transposed = new Array(numCols).fill(null).map(() => new Array(numRows));
+
+   for (let row = 0; row < numRows; row++) {
+     for (let col = 0; col < numCols; col++) {
+       transposed[col][row] = array[row][col];
+     }
+   }
+
+   return transposed;
+   }
+
+
+
+  module.exports = transpose;
+