solution.js

/**
 * @param {string[]} deadends
 * @param {string} target
 * @return {number}
 */
// BFS
var openLock = function (deadends, target) {
    const deadMap = {};
    for (let i = 0; i < deadends.length; i++) {
        deadMap[deadends[i]] = true;
    }
    if (deadMap['0000'] || deadends[target]) {
        return -1;
    }

    const usedMap = {
        '0000': true,
    };
    let sequence = [
        '0000', ];
    let result = 0;
    while (true) {
        if (sequence.length === 0) {
            return -1;
        }

        const nextSequence = [];
        for (let i = 0; i < sequence.length; i++) {
            if (sequence[i] === target) {
                return result;
            }
            const num = sequence[i];
            for (let j = 0; j < 4; j++) {
                // 构造相邻接点
                const prefix = num.substring(0, j);
                const suffix = num.substring(j + 1);
                const digit = +num[j];

                const num1 = `${prefix}${digit === 9 ? '0' : digit + 1}${suffix}`;
                const num2 = `${prefix}${digit === 0 ? '9' : digit - 1}${suffix}`;

                if (!usedMap[num1] && !deadMap[num1]) {
                    usedMap[num1] = true;
                    nextSequence.push(num1);
                }

                if (!usedMap[num2] && !deadMap[num2]) {
                    usedMap[num2] = true;
                    nextSequence.push(num2);
                }
            }
        }

        sequence = nextSequence;

        result++;
    }
};