• https://leetcode.com/problems/arithmetic-slices/description/
• 413. Arithmetic Slices

JavaScript 解答

var numberOfArithmeticSlices = function (A) {
        if (A.length < 3) return 0;
        var dp = [];
        if (A[2] - A[1] === A[1] - A[0]) {
            dp[2] = 1;
        } else {
            dp[2] = 0;
        }
        var result = dp[2];

        for (var i = 3; i < A.length; i++) {
            if (A[i] - A[i - 1] === A[i - 1] - A[i - 2]) {
                dp[i] = dp[i - 1] + 1;
                result += dp[i];
            } else {
                dp[i] = 0;
            }
        }

        return result;
};

• https://leetcode.com/problems/partition-equal-subset-sum/description/
• 416. Partition Equal Subset Sum

JavaScript 解答

var canPartition = function (nums) {
    var sum = nums.reduce((a, b) => a + b, 0);
    if (sum % 2) return false;
    sum = sum / 2;

    var n = nums.length;
    var dp = [];

    while (dp.push(new Array(sum + 1).fill(0)) < n + 1) ;


    for (var i = 0; i < n + 1; i++) {
        dp[i][0] = 1;
    }

    for (var i = 1; i < n + 1; i++) {
        for (var j = 1; j < sum + 1; j++) {
            if (dp[i - 1][j]) dp[i][j] = 1;
            if (j >= nums[i - 1] && dp[i - 1][j - nums[i - 1]]) dp[i][j] = 1;
        }
    }

    // console.log(dp);

    return !!dp[n][sum];

};