【算法】螺旋矩阵

力扣54

双百答案

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector <int> res;
        if (matrix.empty()) return res;
        int rl=0, rh=matrix.size()-1;//rl上，rh下
        int cl=0, ch=matrix[0].size()-1;//cl左， ch右
        while(1){
            for(int i=cl;i<=ch;i++) res.push_back(matrix[rl][i]);
            if(++rl>rh)break;
            for(int i=rl;i<=rh;i++) res.push_back(matrix[i][ch]);
            if(--ch<cl)break;
            for(int i=ch;i>=cl;i--) res.push_back(matrix[rh][i]);
            if(--rh<rl)break;
            for(int i=rh;i>=rl;i--) res.push_back(matrix[i][cl]);
            if(++cl>ch)break;

        }
        return res;

    }
};

力扣59

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector< vector<int> > res(n,vector<int>(n, 0));
        if(n==0) return {{}};
        int up=0, down=n-1;
        int l=0, r=n-1;
        int num=0;
        while(l<=r&&up<=down){
            for(int i=l;i<=r;i++) res[up][i]=++num;
            if(++up>down) break;
            for(int i=up;i<=down;i++) res[i][r]=++num;
            if(--r<l) break;
            for(int i=r;i>=l;i--) res[down][i]=++num;
            if(--down<up) break;
            for(int i=down;i>=up;i--) res[i][l]=++num;
            if(++l>r)break;
        }
        return res;
    }
};

力扣855

class Solution {
public:
    vector<vector<int>> spiralMatrixIII(int R, int C, int r0, int c0) {
        vector<vector<int> > res;
        int l=c0, r=c0, up=r0, down=r0;
        while(l>=0||r<C||up>=0||down<R){
            if(r<C)
                for(int i=max(up+1, 0);i<min(down,R);i++)
                    res.push_back({i, r});
            if(down<R)
                for(int i=min(C-1, r);i>=max(0, l);i--)
                    res.push_back({down, i});
            if(l>=0&&r>l)
                for(int i=min(R-1, down-1); i>=max(0, up+1); i--)
                    res.push_back({i,l});
            if(down>up&&up>=0)
                for(int i=max(0, l);i<=min(C-1, r);i++)
                    res.push_back({up, i});

            up--;
            down++;
            l--;
            r++;
        }
        // while(1){
        //     for(int i=max(l, 0);i<=min(r, C);i++)res.push_back({up,i});
        //     if(++up>down) break;
        //     for(int i=max(up, 0);i<=min(down, R);i++)res.push_back({i, r});
        //     if(--r<l)break;
        //     for(int i=min(r, C);i>=max(l, 0);i--)res.push_back({down,i});
        //     if(--down<up)break;
        //     for(int i=min(R, down);i>=max(up,0);i--)res.push_back({i, l});
        //     if(++l>r)break;
        // } 
        return res;
    }
};