67 lines
2.6 KiB
TypeScript
67 lines
2.6 KiB
TypeScript
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export type State = "." | "#" | "?";
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export class Solver {
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private memo = new Map<string, number>();
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constructor(public map: State[], public groups: number[]) { }
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private everyInRange(start: number, end: number, fn: (ch: string) => boolean): boolean {
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for (let i = start; i < end; i++) {
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if (!fn(this.map[i])) {
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return false;
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}
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}
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return true;
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}
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solve(mapStartIndex: number, groupsStartIndex: number): number {
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const memoKey = `${mapStartIndex},${groupsStartIndex}`;
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if (this.memo.has(memoKey)) {
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return this.memo.get(memoKey)!;
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}
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// const map = this.map.slice(mapStartIndex);
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// console.log("solve", mapStartIndex, groupsStartIndex, map.join(""), this.groups.slice(groupsStartIndex).join(","));
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if (this.groups.length <= groupsStartIndex) {
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const result = this.everyInRange(mapStartIndex, this.map.length, ch => ch != "#") ? 1 : 0;
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this.memo.set(memoKey, result);
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return result;
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}
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// advance while '.' is ended.
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let idx = mapStartIndex;
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while (idx < this.map.length && this.map[idx] == '.') {
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idx++;
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}
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if (idx > mapStartIndex) {
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// console.log(`eat '.' ${idx} times`)
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const result = this.solve(idx, groupsStartIndex);
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this.memo.set(memoKey, result);
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return result;
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}
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// so, first element must not be '.'
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const group = this.groups[groupsStartIndex];
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// locate group
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if (this.map.length - mapStartIndex < group) {
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this.memo.set(memoKey, 0);
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return 0;
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}
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let misf = 0;
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if (
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this.everyInRange(mapStartIndex, mapStartIndex + group, ch => ch != ".") &&
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// this.map.slice(mapStartIndex, mapStartIndex + group).every(x => x != '.') &&
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(this.map.length - mapStartIndex <= group || this.map[group + mapStartIndex] != "#")) {
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// console.log(`locate # ${group} at ${this.groups.slice(groupsStartIndex).join(",")}`);
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misf = this.solve(mapStartIndex + group + 1, groupsStartIndex + 1);
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}
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// if map starts with '#', group must be placed.
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if (this.map[mapStartIndex] == "#") {
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this.memo.set(memoKey, misf);
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return misf;
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}
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// or we add ways not to place group at first element.
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const result = misf + this.solve(1 + mapStartIndex, groupsStartIndex);
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this.memo.set(memoKey, result);
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return result;
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}
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}
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