38 lines
867 B
JavaScript
38 lines
867 B
JavaScript
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// https://www.freecodecamp.org/learn/coding-interview-prep/algorithms/no-repeats-please
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function permAlone(str) {
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let noRepeatsCount = 0;
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noRepeatsCount += Number(!/(.{1})\1/.test(str));
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function swap(Arr, iA, iB) {
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const tmp = Arr[iA];
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Arr[iA] = Arr[iB];
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Arr[iB] = tmp;
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}
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const strArr = str.split("");
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const strLength = strArr.length;
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// Heap's Algorithm as explained @ https://www.baeldung.com/cs/array-generate-all-permutations
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const c = Array(strLength).fill(0);
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let i = 0;
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while (i < strLength) {
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if (c[i] < i) {
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if (i % 2) {
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swap(strArr, c[i], i);
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} else {
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swap(strArr, 0, i);
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}
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noRepeatsCount += Number(!/(.{1})\1/.test(strArr.join("")));
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c[i]++;
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i = 0;
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} else {
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c[i] = 0;
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i++;
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}
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}
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return noRepeatsCount;
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}
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console.log(permAlone("abcdefa"));
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