add new solutions

solutions/32/q3212/solution.go

@@ -0,0 +1,52 @@
+// Package q3212 implements a solution for https://leetcode.com/problems/count-submatrices-with-equal-frequency-of-x-and-y/
+package q3212
+
+type State struct {
+	x, y, dot uint32
+}
+
+func (s *State) Add(another *State) {
+	s.x += another.x
+	s.y += another.y
+	s.dot += another.dot
+}
+
+func (s *State) Sub(another *State) {
+	s.x -= another.x
+	s.y -= another.y
+	s.dot -= another.dot
+}
+
+func numberOfSubmatrices(grid [][]byte) int {
+	cntPrev, cntCur := make([]State, len(grid[0])), make([]State, len(grid[0]))
+
+	submatrices := 0
+	for row := range grid {
+		for col := range grid[0] {
+			st := State{}
+			switch grid[row][col] {
+			case 'X':
+				st.x = 1
+			case 'Y':
+				st.y = 1
+			case '.':
+				st.dot = 1
+			}
+
+			cntCur[col] = st
+			cntCur[col].Add(&cntPrev[col])
+			if col > 0 {
+				cntCur[col].Add(&cntCur[col-1])
+				cntCur[col].Sub(&cntPrev[col-1])
+			}
+
+			if cntCur[col].x > 0 && cntCur[col].y == cntCur[col].x {
+				submatrices++
+			}
+		}
+		cntPrev, cntCur = cntCur, cntPrev
+	}
+	return submatrices
+}
+
+var _ = numberOfSubmatrices