算法菜鸡备战3月2日传智杯省赛----0221

2209. 用地毯覆盖后的最少白色砖块 - 力扣（LeetCode）

力扣每日一题

class Solution {
public:
    // 白色最少 == 黑色最多
    int minimumWhiteTiles(string floor, int numCarpets, int carpetLen) {
        int n = floor.size();
        // 记忆化搜索
        vector memo(n + 1, vector<int>(numCarpets + 1, -1));
        auto dfs = [&](this auto&& dfs, int x, int y) {
            // 有y块地毯和x块砖，求对应的黑色最大值
            if (x <= y * carpetLen) {
                // 铺满了
                return x;
            }
            if (memo[x - 1][y] != -1) {
                // 记忆化搜索
                return memo[x - 1][y];
            }
            int& res = memo[x - 1][y];
            if (floor[x - 1] == '0') {
                // 遇到黑色
                return res = 1 + dfs( x - 1, y);
            }
            return res = max(
                       (y > 0 ? dfs( x - carpetLen, y - 1) + carpetLen : 0),
                       dfs( x - 1, y));
        };
        return n - dfs( n, numCarpets);
    }
};

2

2560. 打家劫舍 IV - 力扣（LeetCode）

class Solution {
public:
    int minCapability(vector<int>& nums, int k) {
        int left = 0, right = *max_element(nums.begin(), nums.end()),
            n = nums.size();
        auto check = [&](int mid) {
            int tmp = 0;
            for (int i = 0; i < n; i++) {
                if (nums[i] <= mid) {
                    i++;
                    tmp++;
                    if (tmp >= k) {
                        return true;
                    }
                }
            }
            cout << tmp << endl;

            return false;
        };
        while (left <= right) {
            // cout << left << ' ' << right << endl;
            int mid = (left + right) >> 1;
            if (check(mid)) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return left;
    }
};

3

778. 水位上升的泳池中游泳 - 力扣（LeetCode）

class Solution {
public:
    int m[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
    int swimInWater(vector<vector<int>>& grid) {
        int n = grid.size();
        if(n == 1){
            return grid[0][0];
        }
        int left = grid[0][0], right = 2500;
        auto bfs = [&](int mid) {
            queue<pair<int, int>> q;
            vector t(n, vector<bool>(n, false));
            q.push({0, 0});
            int qx, qy, x, y;
            while (q.size()) {
                auto [qx, qy] = q.front();
                q.pop();
                for (int i = 0; i < 4; i++) {
                    x = qx + m[i][0], y = qy + m[i][1];
                    if (x < 0 || x >= n || y < 0 || y >= n || t[x][y])
                        continue;
                    if (grid[x][y] > mid)
                        continue;
                    if (x == n - 1 && y == n - 1)
                        return true;
                    t[x][y] = true;
                    q.push({x, y});
                }
            }
            return false;
        };
        while (left <= right) {
            int mid = (left + right) >> 1;
            if (bfs(mid)) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return left;
    }
};

4

2616. 最小化数对的最大差值 - 力扣（LeetCode）

class Solution {
public:
    int minimizeMax(vector<int>& nums, int p) {
        if(p == 0) return 0;
        ranges::sort(nums);
        int n = nums.size();
        vector<int> tmp(n - 1);
        for(int i = 1;i <n;i++){
            tmp[i - 1] = nums[i] - nums[i - 1];
        }
        n--;
        int left = 0,right = *max_element(nums.begin(),nums.end());
        auto check = [&](int mid){
            int a = 0;
            for(int i = 0;i < n;i++){
                if(tmp[i] <= mid){
                    i++;
                    a++;
                    if(a >= p){
                        return true;
                    }
                }
            }
            return false;
        };
        while(left <= right){
            int mid = (left + right) >> 1;
            if(check(mid)){
                right = mid - 1;
            }else{
                left = mid + 1;
            }
        }
        return left;
    }
};