@technobuddha/library/longestCommonSubstring/longestCommonSubstring.cjs

A large library of useful functions

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.longestCommonSubstring = void 0;
var create2DArray_1 = __importDefault(require("../create2DArray"));
/**
 * Implementation of Longest Common Substring problem.
 * https://en.wikipedia.org/wiki/Longest_common_substring_problem
 *
 * Returns the longest possible substring that is substring of both of given strings.
 *
 * @param array1 First string.
 * @param array2 Second string.
 * @returns A string that is common to both strings such that there is no
 * common substring with size greater than the length of the string.
 */
function longestCommonSubstring(string1, string2, _a) {
    var _b = _a === void 0 ? {} : _a, _c = _b.caseInsensitive, caseInsensitive = _c === void 0 ? false : _c;
    var ci1 = caseInsensitive ? string1.toLowerCase() : string1;
    var ci2 = caseInsensitive ? string2.toLowerCase() : string2;
    var comparsions = create2DArray_1.default(ci1.length + 1, ci2.length + 1, 0);
    var maxSubStrLength = 0;
    var lastMaxSubStrIndex = -1;
    for (var i = 0; i < ci1.length; ++i) {
        var c1 = ci1.charAt(i);
        for (var j = 0; j < ci2.length; ++j) {
            var c2 = ci2.charAt(j);
            if (c1 === c2) {
                if (i > 0 && j > 0)
                    comparsions[i][j] = comparsions[i - 1][j - 1] + 1;
                else
                    comparsions[i][j] = 1;
            }
            else {
                comparsions[i][j] = 0;
            }
            if (comparsions[i][j] > maxSubStrLength) {
                maxSubStrLength = comparsions[i][j];
                lastMaxSubStrIndex = i;
            }
        }
    }
    return string1.slice(lastMaxSubStrIndex - maxSubStrLength + 1, lastMaxSubStrIndex + 1);
}
exports.longestCommonSubstring = longestCommonSubstring;
exports.default = longestCommonSubstring;