No.216 - LeetCode[74] Search a 2D Matrix - 排序矩阵双向二分检索

/*
 * @lc app=leetcode id=74 lang=cpp
 *
 * [74] Search a 2D Matrix
 */

// @lc code=start
class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int N = matrix.size();
        if(N <= 0) return false;
        int M = matrix[0].size();
        if(M <= 0) return false;
        int a = bisearchN(0,N,target,matrix);
        if(a == -1) return false;
        int b = bisearchM(0,M,target,matrix[a]);
        if(b == -1) return false;
        return true;
    }
    int bisearchN(int L,int R,int K,vector<vector<int>>& T){
        if( L+1 >= R ){
            if(T[L][0] <= K) return L;
            return L-1;
        }
        int mid = (L+R)/2;
        if(T[mid][0] <= K){
            return bisearchN(mid,R,K,T);
        }
        return bisearchN(L,mid,K,T);
    }
    int bisearchM(int L,int R,int K,vector<int>& T){
        if( L+1 >= R){
            if(T[L] == K) return L;
            return -1;
        }
        int mid = (L+R)/2;
        if(T[mid] <= K){
            return bisearchM(mid,R,K,T);
        }
        return bisearchM(L,mid,K,T);
    }
};
// @lc code=end