What

Brief

This is a standalone Stack data structure from the data-structure-typed collection. If you wish to access more data structures or advanced features, you can transition to directly installing the complete data-structure-typed package

How

install

npm

npm i stack-typed --save

yarn

yarn add stack-typed

snippet

Balanced Parentheses or Brackets

    type ValidCharacters = ')' | '(' | ']' | '[' | '}' | '{';

    const stack = new Stack<string>();
    const input: ValidCharacters[] = '[({})]'.split('') as ValidCharacters[];
    const matches: { [key in ValidCharacters]?: ValidCharacters } = { ')': '(', ']': '[', '}': '{' };
    for (const char of input) {
      if ('([{'.includes(char)) {
        stack.push(char);
      } else if (')]}'.includes(char)) {
        if (stack.pop() !== matches[char]) {
          fail('Parentheses are not balanced');
        }
      }
    }
    console.log(stack.isEmpty()); // true

Expression Evaluation and Conversion

    const stack = new Stack<number>();
    const expression = [5, 3, '+']; // Equivalent to 5 + 3
    expression.forEach(token => {
      if (typeof token === 'number') {
        stack.push(token);
      } else {
        const b = stack.pop()!;
        const a = stack.pop()!;
        stack.push(token === '+' ? a + b : 0); // Only handling '+' here
      }
    });
    console.log(stack.pop()); // 8

Depth-First Search (DFS)

    const stack = new Stack<number>();
    const graph: { [key in number]: number[] } = { 1: [2, 3], 2: [4], 3: [5], 4: [], 5: [] };
    const visited: number[] = [];
    stack.push(1);
    while (!stack.isEmpty()) {
      const node = stack.pop()!;
      if (!visited.includes(node)) {
        visited.push(node);
        graph[node].forEach(neighbor => stack.push(neighbor));
      }
    }
    console.log(visited); // [1, 3, 5, 2, 4]

Backtracking Algorithms

    const stack = new Stack<[number, number]>();
    const maze = [
      ['S', ' ', 'X'],
      ['X', ' ', 'X'],
      [' ', ' ', 'E']
    ];
    const start: [number, number] = [0, 0];
    const end = [2, 2];
    const directions = [
      [0, 1], // To the right
      [1, 0], // down
      [0, -1], // left
      [-1, 0] // up
    ];

    const visited = new Set<string>(); // Used to record visited nodes
    stack.push(start);
    const path: number[][] = [];

    while (!stack.isEmpty()) {
      const [x, y] = stack.pop()!;
      if (visited.has(`${x},${y}`)) continue; // Skip already visited nodes
      visited.add(`${x},${y}`);

      path.push([x, y]);

      if (x === end[0] && y === end[1]) {
        break; // Find the end point and exit
      }

      for (const [dx, dy] of directions) {
        const nx = x + dx;
        const ny = y + dy;
        if (
          maze[nx]?.[ny] === ' ' || // feasible path
          maze[nx]?.[ny] === 'E' // destination
        ) {
          stack.push([nx, ny]);
        }
      }
    }

    expect(path).toContainEqual(end);

Function Call Stack

    const functionStack = new Stack<string>();
    functionStack.push('main');
    functionStack.push('foo');
    functionStack.push('bar');
    console.log(functionStack.pop()); // 'bar'
    console.log(functionStack.pop()); // 'foo'
    console.log(functionStack.pop()); // 'main'

Simplify File Paths

    const stack = new Stack<string>();
    const path = '/a/./b/../../c';
    path.split('/').forEach(segment => {
      if (segment === '..') stack.pop();
      else if (segment && segment !== '.') stack.push(segment);
    });
    console.log(stack.elements.join('/')); // 'c'

Stock Span Problem

    const stack = new Stack<number>();
    const prices = [100, 80, 60, 70, 60, 75, 85];
    const spans: number[] = [];
    prices.forEach((price, i) => {
      while (!stack.isEmpty() && prices[stack.peek()!] <= price) {
        stack.pop();
      }
      spans.push(stack.isEmpty() ? i + 1 : i - stack.peek()!);
      stack.push(i);
    });
    console.log(spans); // [1, 1, 1, 2, 1, 4, 6]

API docs & Examples

API Docs

Live Examples

Examples Repository

Data Structures

Data Structure	Unit Test	Performance Test	API Docs
Stack			Stack

Standard library data structure comparison

Benchmark

Built-in classic algorithms

Software Engineering Design Standards