Into the Dynamic Programming

Author: prabaprakash

coin-change.js

@@ -0,0 +1,93 @@
+'use strict';
+
+const fs = require('fs');
+
+process.stdin.resume();
+process.stdin.setEncoding('utf-8');
+
+let inputString = '';
+let currentLine = 0;
+
+process.stdin.on('data', function (inputStdin) {
+    inputString += inputStdin;
+});
+
+process.stdin.on('end', function () {
+    inputString = inputString.split('\n');
+
+    main();
+});
+
+function readLine() {
+    return inputString[currentLine++];
+}
+
+/*
+ * Complete the 'getWays' function below.
+ *
+ * The function is expected to return a LONG_INTEGER.
+ * The function accepts following parameters:
+ *  1. INTEGER n
+ *  2. LONG_INTEGER_ARRAY c
+ */
+
+function getWays(n, c) {
+    // Write your code here
+    return count(c, c.length, n);
+}
+function readLine() {
+    return inputString[currentLine++];
+}
+let memory = {}
+function count(S, m, n) {
+    // If n is 0 then there is 1 solution 
+    // (do not include any coin) 
+    if (n === 0)
+        return 1;
+
+    // If n is less than 0 then no 
+    // solution exists 
+    if (n < 0)
+        return 0;
+
+    // If there are no coins and n 
+    // is greater than 0, then no 
+    // solution exist 
+    if (m <= 0 && n >= 1)
+        return 0;
+
+    // count is sum of solutions (i) 
+    // including S[m-1] (ii) excluding S[m-1] 
+    // return count(S, m - 1, n) + count(S, m, n - S[m - 1]);
+
+    let leftsubtree = m - 1 + '-' + n;
+    let rightsubtree = m + '-' + (n - S[m - 1]);
+
+    if (typeof memory[leftsubtree] === 'undefined')
+        memory[leftsubtree] = count(S, m - 1, n);
+
+    if (typeof memory[rightsubtree] === 'undefined')
+        memory[rightsubtree] = count(S, m, n - S[m - 1]);
+
+    return memory[leftsubtree] + memory[rightsubtree];
+}
+
+function main() {
+    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);
+
+    const firstMultipleInput = readLine().replace(/\s+$/g, '').split(' ');
+
+    const n = parseInt(firstMultipleInput[0], 10);
+
+    const m = parseInt(firstMultipleInput[1], 10);
+
+    const c = readLine().replace(/\s+$/g, '').split(' ').map(cTemp => parseInt(cTemp, 10));
+
+    // Print the number of ways of making change for 'n' units using coins having the values given by 'c'
+
+    const ways = getWays(n, c);
+
+    ws.write(ways + '\n');
+
+    ws.end();
+}