Week Training: 413 Arithmetic Slices

richard978

于 2017-05-28 15:33:02 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/richard978/article/details/72793305

本文介绍了一种使用动态规划解决算术切片计数问题的方法。通过定义dp[i]为数组中直到位置i的算术切片数量，并利用状态转移方程dp[i] = dp[i-1] + 1来更新切片数量，最终实现了有效求解。

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Many ways to do, using dp, we can let dp[i] be the number of slices until i in the array, so the state transformation is dp[i]=dp[i-1]+1, when the new number is able to make a arithmetic slice with before. The total number is to add numbers of each position until the last element.

class Solution {
public:
    int numberOfArithmeticSlices(vector<int>& A) {
        int l = A.size();
        vector<int> dp(l);
        int num = 0;
        for(int i=0;i<l;i++){
            dp[i]=0;
        }
        for(int i=2;i<l;i++){
            if(A[i-1]-A[i-2]==A[i]-A[i-1]){
                dp[i] = dp[i-1]+1;
            }
            num += dp[i];
        }
        return num;
    }
};