题目： 

 

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解析： 

 

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代码： 

public int numberOfArithmeticSlices(int[] nums) {
        int n = nums.length;
        int[] dp = new int[n];

        int ret = 0;
        for(int i = 2; i < n; i++){
            dp[i] = nums[i] - nums[i-1] == nums[i-1] - nums[i-2] ? dp[i-1]+1 : 0;
            ret += dp[i];
        }

        return ret;
    }