typescript-algorithms-and-datastructures/dist/FindMaximumSubarray.js

Useful algorithms and Data structures written in typescript.

(function (factory) {
    if (typeof module === "object" && typeof module.exports === "object") {
        var v = factory(require, exports);
        if (v !== undefined) module.exports = v;
    }
    else if (typeof define === "function" && define.amd) {
        define(["require", "exports"], factory);
    }
})(function (require, exports) {
    "use strict";
    Object.defineProperty(exports, "__esModule", { value: true });
    function FindMaximumSubarray(array, left = 0, right = array.length) {
        if (left === right) {
            return [left, right, left > array.length ? -Infinity : array[left]];
        }
        else {
            const middle = Math.floor((left + right) / 2);
            const [leftLow, leftHigh, leftSum] = FindMaximumSubarray(array, left, middle);
            const [rightLow, rightHigh, rightSum] = FindMaximumSubarray(array, middle + 1, right);
            const [crossLow, crossHigh, crossSum] = FindMaximumCrossingSubarray(array, left, middle, right);
            if (leftSum >= rightSum && leftSum >= crossSum) {
                return [leftLow, leftHigh, leftSum];
            }
            if (rightSum >= leftSum && rightSum >= crossSum) {
                return [rightLow, rightHigh, rightSum];
            }
            return [crossLow, crossHigh, crossSum];
        }
    }
    function FindMaximumCrossingSubarray(array, left, middle, right) {
        let leftSum = -Infinity;
        let rightSum = -Infinity;
        let sum = 0;
        let maxLeft = middle;
        let maxRight = Math.min(middle + 1, array.length - 1);
        for (let i = middle; i >= left; i--) {
            sum = sum + array[i];
            if (sum > leftSum) {
                leftSum = sum;
                maxLeft = i;
            }
        }
        sum = 0;
        for (let i = middle + 1; i < right; i++) {
            sum = sum + array[i];
            if (sum > rightSum) {
                rightSum = sum;
                maxRight = i;
            }
        }
        return [maxLeft, maxRight, Math.max(rightSum, 0) + Math.max(leftSum, 0)];
    }
    exports.default = FindMaximumSubarray;
});
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