博客中的练习题解答

题目需要思考了才有价值, 所以在我的博客中给出的练习题都不直接给答案, 在这里进行集中解答. 有需要者自取.

Py1

A = np.array([
[1, 1, 1, 5, 5, 5],
[1, 1, 1, 5, 5, 5],
[4, 4, 4, 6, 6, 6],
[4, 4, 4, 6, 6, 6]
])
B = np.lib.stride_tricks.as_strided(A, shape=(2,2,2,3), strides=(48,12,24,4))
print(B)

包含min函数的栈

import java.util.Stack;

public class Solution {
    
    Stack<Integer> dataStack = new Stack<>();
    Stack<Integer> minStack = new Stack<>();
    
    public void push(int node) {
        dataStack.push(node);
        if(minStack.isEmpty() || node <= minStack.peek()) {
            minStack.push(node);
        }
    }
    
    public void pop() {
        int out = dataStack.pop();
        if(out == minStack.peek()) {
            minStack.pop();
        }
    }
    
    public int top() {
        return dataStack.peek();
    }
    
    public int min() {
        return minStack.peek();
    }
}

所有奇数长度子数组的和

Leetcode 1588

class Solution {
public:
    int sumOddLengthSubarrays(vector<int>& arr) {
        int len = arr.size();
        vector<int> preSum(len+1);
        for(int i=1; i<=len; ++i) {
            preSum[i] = preSum[i-1] + arr[i-1];
        }
        int sum = 0;
        for(int k=1; k<=len; k+=2) {
            for(int j=k; j<=len; ++j) {
                sum += preSum[j]-preSum[j-k];
            }
        }
        return sum;
    }
};

Accumulation of English writing by examples

1. C