John.peter

src/brackets/index.js

@@ -4,6 +4,37 @@
  * @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 = 0; i < str.length; i++) {
+        let x = str[i];
+
+        if ( x == '[' || x == '{' || x == '(') {
+            stack.push(x);
+              continue;
+        }
+
+            if (stack.length === 0 )
+              return "invalid"
+
+        const poppedELEMENT = stack.pop();
+        if (x == ']' && poppedELEMENT != '['){
+           return "invalid"
+        }
+        if (x == '}' && poppedELEMENT != '{') {
+            return "invalid"
+        };
+        if (x == ')' && poppedELEMENT != '(') {
+            return "invalid"
+        };
+
+
+    };
+
+    return stack.length === 0 ? "valid" : "invalid"
+};
+
 
 module.exports = isValid;

src/roman-numerals/index.js

@@ -4,6 +4,39 @@
  * @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 curSym = numeral[roman[i]]
+      let nextSym = numeral[roman[i + 1]]
+
+      if(nextSym && nextSym > curSym){
+          result += nextSym  - curSym
+           i++
+      }
+       else {
+          result += curSym
+    };
+  };
+    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((cur) => cur[index]))
+
+};
 
 module.exports = transpose;