1536. Minimum Swaps to Arrange a Binary Grid
Given an n x n binary grid, in one step you can choose two adjacent rows of the grid and swap them.
A grid is said to be valid if all the cells above the main diagonal are zeros.
Return the minimum number of steps needed to make the grid valid, or -1 if the grid cannot be valid.
The main diagonal of a grid is the diagonal that starts at cell (1, 1) and ends at cell (n, n).
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| class Solution {
public:
int minSwaps(vector<vector<int>>& A) {
vector<int> counter;
int n = A.size(), m = A[0].size();
for(int i = 0; i < n; i++) {
int cnt = 0;
for(int j = m - 1; j >= 0; j--) {
if(A[i][j] == 0) cnt++;
else break;
}
counter.push_back(cnt);
}
int req = m - 1, res = 0;
for(int i = 0; req; i++,req--) {
int find = -1;
for(int j = i; j < n; j++) {
if(counter[j] >= req) {
find = j;
break;
}
}
if(find == -1) return -1;
res += find - i;
while(find != i) {
swap(counter[find - 1], counter[find]);
find--;
}
}
return res;
}
};
|
