365天挑战LeetCode1000题——Day 025 每日一题 + 昨日每日一题 + 二分查找 03

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741. 摘樱桃（131）

代码实现（看题解）

class Solution {
public:
    int cherryPickup(vector<vector<int>> &grid) {
        int n = grid.size();
        vector<vector<vector<int>>> f(n * 2 - 1, vector<vector<int>>(n, vector<int>(n, INT_MIN)));
        f[0][0][0] = grid[0][0];
        for (int k = 1; k < n * 2 - 1; ++k) {
            for (int x1 = max(k - n + 1, 0); x1 <= min(k, n - 1); ++x1) {
                int y1 = k - x1;
                if (grid[x1][y1] == -1) {
                    continue;
                }
                for (int x2 = x1; x2 <= min(k, n - 1); ++x2) {
                    int y2 = k - x2;
                    if (grid[x2][y2] == -1) {
                        continue;
                    }
                    int res = f[k - 1][x1][x2]; // 都往右
                    if (x1) {
                        res = max(res, f[k - 1][x1 - 1][x2]); // 往下，往右
                    }
                    if (x2) {
                        res = max(res, f[k - 1][x1][x2 - 1]); // 往右，往下
                    }
                    if (x1 && x2) {
                        res = max(res, f[k - 1][x1 - 1][x2 - 1]); // 都往下
                    }
                    res += grid[x1][y1];
                    if (x2 != x1) { // 避免重复摘同一个樱桃
                        res += grid[x2][y2];
                    }
                    f[k][x1][x2] = res;
                }
            }
        }
        return max(f.back().back().back(), 0);
    }
};

873. 最长的斐波那契子序列的长度（二刷）

代码实现（二刷自解）

class Solution {
public:
    int lenLongestFibSubseq(vector<int>& arr) {
        unordered_map<int, int> myMap;
        int n = arr.size();
        for (int i = 0; i < n; i++) {
            myMap[arr[i]] = i;
        }
        vector<vector<int>> dp(n, vector<int>(n, 0));
        int ans = 0;
        for (int i = 1; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                int firstNum = arr[j] - arr[i];
                if (firstNum >= arr[i]) continue;
                if (myMap.count(firstNum)) {
                    int index = myMap[firstNum];
                    dp[j][i] = max(dp[i][index] + 1, 3);
                    ans = max(dp[j][i], ans);
                }
            }
        }
        return ans;
    }
};

1760. 袋子里最少数目的球（132）

代码实现（看题解）

class Solution {
public:
    int minimumSize(vector<int>& nums, int maxOperations) {
        int l = 0;
        int r = *max_element(nums.begin(), nums.end()) + 1;
        while (l + 1 != r) {
            int m = l + r >> 1;
            int pos = 0;
            for (int num : nums) {
                pos += (num - 1) / m;
            }
            if (pos <= maxOperations) r = m;
            else l = m;
        }
        return r;
    }
};

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