Create 756-pyramid-transition-matrix.js

Author: everthis

756-pyramid-transition-matrix.js

@@ -0,0 +1,32 @@
+/**
+ * @param {string} bottom
+ * @param {string[]} allowed
+ * @return {boolean}
+ */
+const pyramidTransition = function (bottom, allowed) {
+  const map = new Map()
+  allowed.map((item) => {
+    const t = map.get(item[0] + item[1]) || new Array()
+    t.push(item[2])
+    map.set(item[0] + item[1], t)
+  })
+  const memo = new Map()
+  const solve = function (cur, ind, next) {
+    if (memo.has(cur)) return memo.get(cur)
+    if (cur.length === 1) return true
+    if (ind >= cur.length - 1) {
+      const res = solve(next, 0, '')
+      memo.set(next, res)
+      return res
+    }
+    if (!map.has(cur.slice(ind, ind + 2))) {
+      memo.set(cur, false)
+      return false
+    }
+    for (let char of map.get(cur.slice(ind, ind + 2))) {
+      if (solve(cur, ind + 1, next + char)) return true
+    }
+    return false
+  }
+  return solve(bottom, 0, '')
+}