LC 1504. Count Submatrices With All Ones

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Solution1:

class Solution {
public:
    int m;
    int n;
    int numSubmat(vector<vector<int>>& mat) {
        m=mat.size();
        n=mat[0].size();
        int res=0;
        for(int up=0;up<m;up++){
            vector<int> allone(n,1);
            for(int down=up;down<m;down++){
                for(int i=0;i<n;i++){
                    allone[i]&=mat[down][i];
                }
                res+=getcnt(allone);
            }
        }
        return res;
    }
    
    int getcnt(vector<int>& allone){
        int res=0;
        int len=0;
        for(int i=0;i<n;i++){
            len=allone[i]==0?0:len+1;
            res+=len;
        }
        return res;
    }
};

Solution2:

class Solution {
public:
    int m;
    int n;
    int numSubmat(vector<vector<int>>& mat) {
        m=mat.size();
        n=mat[0].size();
        vector<int> col(n);
        int res=0;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                col[j]=mat[i][j]==0?0 :col[j]+1;
            }
            res+=getcnt(col);
        }
        return res;
    }
    
    int getcnt(vector<int>& col){
        stack<int> stk;
        vector<int> cnt(n);
        int res=0;
        for(int i=0;i<n;i++){
            while(!stk.empty() && col[i]<=col[stk.top()]) stk.pop();
            if(stk.empty()){
                cnt[i]=(i+1)*col[i];
                res+=cnt[i];
            }else{
                cnt[i]=cnt[stk.top()]+(i-stk.top())*col[i];
                res+=cnt[i];
            }
            stk.push(i);
        }
        return res;
    }
};