525. 连续数组

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leading to the advanced question

Solution Tips

方案一: 转化 + 前缀和 + 哈希表

var findMaxLength = function(nums) {
    let maxLength = 0;
    const map = new Map();
    let counter = 0;
    map.set(counter, -1);
    const n = nums.length;
    for (let i = 0; i < n; i++) {
        const num = nums[i];
        if (num == 1) {
            counter++;
        } else {
            counter--;
        }
        if (map.has(counter)) {
            const prevIndex = map.get(counter);
            maxLength = Math.max(maxLength, i - prevIndex);
        } else {
            map.set(counter, i);
        }
    }
    return maxLength;
};