Create 2286-booking-concert-tickets-in-groups.js

Author: everthis

2286-booking-concert-tickets-in-groups.js

@@ -0,0 +1,123 @@
+/**
+ * @param {number} n
+ * @param {number} m
+ */
+function BookMyShow(n, m) {
+    let a = Array(n).fill(0), st = new SegmentTreeRMQ(a), fen = new Fenwick(n + 3);
+    for (let i = 0; i < n; i++) fen.update(i, m);
+    return { gather, scatter }
+    function gather(k, maxRow) {
+        let idx = st.indexOf(0, m - k);
+        if (idx == -1 || idx > maxRow) return [];
+        let min = st.minx(idx, idx + 1);
+        st.update(idx, min + k);
+        fen.update(idx, -k);
+        return [idx, min];
+    }
+    function scatter(k, maxRow) {
+        let totToMaxRow = fen.query(maxRow);
+        if (totToMaxRow < k) return false;
+        while (k > 0) {
+            let idx = st.indexOf(0, m - 1);
+            if (idx == -1 || idx > maxRow) break;
+            let min = st.minx(idx, idx + 1);
+            let use = Math.min(k, m - min);
+            k -= use;
+            st.update(idx, min + use);
+            fen.update(idx, -use);
+        }
+        return true;
+    }
+}
+
+/** 
+ * Your BookMyShow object will be instantiated and called as such:
+ * var obj = new BookMyShow(n, m)
+ * var param_1 = obj.gather(k,maxRow)
+ * var param_2 = obj.scatter(k,maxRow)
+ */
+////////////////////////////////////////////////// Template ////////////////////////////////////////////////////////////////////
+function Fenwick(n) {
+    let a = Array(n).fill(0);
+    return { query, update, rangeSum, tree }
+    function query(i) { // [0, i] prefix sum
+        let sum = 0;
+        for (i++; i > 0; i = parent(i)) sum += a[i];
+        return sum;
+    }
+    function update(i, v) {
+        for (i++; i < n; i = next(i)) a[i] += v;
+    }
+    function rangeSum(l, r) {
+        return query(r) - query(l - 1);
+    }
+    function parent(x) {
+        return x - lowestOneBit(x);
+    }
+    function next(x) {
+        return x + lowestOneBit(x);
+    }
+    function lowestOneBit(x) {
+        return x & -x;
+    }
+    function tree() {
+        return a;
+    }
+}
+
+function SegmentTreeRMQ(A) {
+    let n = A.length, h = Math.ceil(Math.log2(n)), len = 2 * 2 ** h, a = Array(len).fill(Number.MAX_SAFE_INTEGER);
+    h = 2 ** h;
+    initializeFromArray();
+    return { update, minx, indexOf, tree }
+    function initializeFromArray() {
+        for (let i = 0; i < n; i++) a[h + i] = A[i];
+        for (let i = h - 1; i >= 1; i--) propagate(i);
+    }
+    function update(pos, v) {
+        a[h + pos] = v;
+        for (let i = parent(h + pos); i >= 1; i = parent(i)) propagate(i);
+    }
+    function propagate(i) {
+        a[i] = Math.min(a[left(i)], a[right(i)]);
+    }
+    function minx(l, r) {
+        let min = Number.MAX_SAFE_INTEGER;
+        if (l >= r) return min;
+        l += h;
+        r += h;
+        for (; l < r; l = parent(l), r = parent(r)) {
+            if (l & 1) min = Math.min(min, a[l++]);
+            if (r & 1) min = Math.min(min, a[--r]);
+        }
+        return min;
+    }
+    function indexOf(l, v) {
+        if (l >= h) return -1;
+        let cur = h + l;
+        while (1) {
+            if (a[cur] <= v) {
+                if (cur >= h) return cur - h;
+                cur = left(cur);
+            } else {
+                cur++;
+                if ((cur & cur - 1) == 0) return -1;
+                if (cur % 2 == 0) cur = parent(cur);
+            }
+        }
+    }
+    function parent(i) {
+        return i >> 1;
+    }
+    function left(i) {
+        return 2 * i;
+    }
+    function right(i) {
+        return 2 * i + 1;
+    }
+    function tree() {
+        return a;
+    }
+}
+//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+