63 lines
1.4 KiB
TypeScript
63 lines
1.4 KiB
TypeScript
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// You are given the following information, but you may prefer to do some research for yourself.
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// 1 Jan 1900 was a Monday.
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// Thirty days has September,
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// April, June and November.
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// All the rest have thirty-one,
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// Saving February alone,
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// Which has twenty-eight, rain or shine.
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// And on leap years, twenty-nine.
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// A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
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// How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?
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export = {};
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interface Date {
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year: number;
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month: number;
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date: number;
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}
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/**
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* Find all of the Sundays in a given
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*/
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const sundaysInAYear = (year: number): Date[] => {
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const time = new Date(year, 0, 1);
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while (time.getDay() != 0) {
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time.setDate(time.getDate() + 1);
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}
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const dates = [];
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while (time.getFullYear() === year) {
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const month = time.getMonth() + 1;
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const date = time.getDate();
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dates.push({
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year,
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month,
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date
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});
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time.setDate(time.getDate() + 7);
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}
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return dates;
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};
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// Output
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let dates: Date[] = [];
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for (let year = 1901; year <= 2000; year++) {
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dates = [...dates, ...sundaysInAYear(year)];
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}
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let count = 0;
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dates.forEach(({ date }) => {
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if (date == 1) {
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count += 1;
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}
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});
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console.log(count);
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