@onesy/algorithms/kmp.js

Algorithms

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const longestPrefixSuffix_1 = __importDefault(require("./longestPrefixSuffix"));
// It goes through the string and matches the value sequence, where value match stops in sequence, based on LPS table of the value,
// it doesn’t go back like naive search to i = 1, but it continues from the same i and continues matching from the j at index where prefix repeated position within the value.
// Complexity: O(n)
function kmp(string, value) {
    const lengthString = string.length;
    const lengthValue = value.length;
    const lps = (0, longestPrefixSuffix_1.default)(value);
    let i = 0;
    let j = 0;
    while (i < lengthString) {
        if (string[i] === value[j]) {
            i++;
            j++;
        }
        else {
            if (j > 0)
                j = lps[j - 1];
            else
                i++;
        }
        if (j === lengthValue)
            return true;
    }
    return false;
}
exports.default = kmp;