R524809
80 lines
1.9 KiB
TypeScript
80 lines
1.9 KiB
TypeScript
/**
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* 纯数学工具（无随机、无平台依赖），供 generators / 模板引擎使用
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*/
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/** 将数值限制在 [min, max] */
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export function clamp(value: number, min: number, max: number): number {
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return Math.min(max, Math.max(min, value));
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}
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/** 最大公约数（非负整数） */
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export function gcd(a: number, b: number): number {
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let x = Math.abs(Math.trunc(a));
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let y = Math.abs(Math.trunc(b));
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while (y !== 0) {
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const t = y;
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y = x % y;
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x = t;
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}
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return x || 1;
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}
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/** 最小公倍数 */
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export function lcm(a: number, b: number): number {
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const g = gcd(a, b);
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return Math.abs(Math.trunc(a) * Math.trunc(b)) / g;
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}
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/** 闭区间 [min, max] 上的整数列表 */
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export function integerRangeInclusive(min: number, max: number): number[] {
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const lo = Math.min(min, max);
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const hi = Math.max(min, max);
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const out: number[] = [];
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for (let i = lo; i <= hi; i += 1) {
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out.push(i);
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}
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return out;
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}
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/** 数组求和 */
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export function sum(numbers: readonly number[]): number {
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let s = 0;
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for (let i = 0; i < numbers.length; i += 1) {
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s += numbers[i];
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}
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return s;
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}
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/** 算术平均（空数组为 0） */
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export function mean(numbers: readonly number[]): number {
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if (numbers.length === 0) return 0;
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return sum(numbers) / numbers.length;
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}
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/** 各位数字之和（十进制，忽略负号） */
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export function digitSum(n: number): number {
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let v = Math.abs(Math.trunc(n));
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let s = 0;
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while (v > 0) {
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s += v % 10;
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v = Math.floor(v / 10);
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}
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return s;
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}
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export function isEven(n: number): boolean {
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return n % 2 === 0;
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}
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export function isOdd(n: number): boolean {
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return !isEven(n);
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}
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/**
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* 将浮点数舍入到指定小数位（避免 0.1+0.2 展示问题）
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*/
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export function roundToDecimals(value: number, decimals: number): number {
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const p = 10 ** decimals;
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return Math.round(value * p) / p;
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}
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