solve search_a_2d_matrix_ii

Author: mind1949

algs/0240.search_a_2d_matrix2.go

@@ -0,0 +1,50 @@
+package algs
+
+// SearchMatrix
+//
+// Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:
+//
+//	Integers in each row are sorted in ascending from left to right.
+//	Integers in each column are sorted in ascending from top to bottom.
+//
+// Example 1:
+//
+// Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5
+// Output: true
+//
+// Example 2:
+//
+// Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20
+// Output: false
+//
+// Constraints:
+//
+//	m == matrix.length
+//	n == matrix[i].length
+//	1 <= n, m <= 300
+//	-10^9 <= matrix[i][j] <= 10^9
+//	All the integers in each row are sorted in ascending order.
+//	All the integers in each column are sorted in ascending order.
+//	-10^9 <= target <= 10^9
+func SearchMatrix(matrix [][]int, target int) bool {
+	// 使用官方题解的 Z字形解法
+	if len(matrix) == 0 {
+		return false
+	}
+
+	m := len(matrix)
+	n := len(matrix[0])
+
+	x, y := 0, n-1
+	for x >= 0 && x < m && y >= 0 && y < n {
+		value := matrix[x][y]
+		if value == target {
+			return true
+		} else if value > target {
+			y--
+		} else {
+			x++
+		}
+	}
+	return false
+}

src/solution.rs

@@ -1,7 +1,10 @@
 /// [Leetcode](https://leetcode.cn) solution
 pub struct Solution;
 
-use std::collections::{HashMap, VecDeque};
+use std::{
+    cmp::Ordering,
+    collections::{HashMap, VecDeque},
+};
 
 impl Solution {
     /// [1. Tow Sum](https://leetcode.cn/problems/two-sum/description)
@@ -1107,4 +1110,48 @@ impl Solution {
             }
         }
     }
+
+    /// [240. Search a 2D Matrix II](https://leetcode.cn/problems/search-a-2d-matrix-ii/description)
+    ///
+    /// Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:
+    ///
+    ///	Integers in each row are sorted in ascending from left to right.
+    ///	Integers in each column are sorted in ascending from top to bottom.
+    ///
+    /// Example 1:
+    ///
+    /// Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5
+    /// Output: true
+    ///
+    /// Example 2:
+    ///
+    /// Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20
+    /// Output: false
+    ///
+    /// Constraints:
+    ///
+    ///	m == matrix.length
+    ///	n == matrix[i].length
+    ///	1 <= n, m <= 300
+    ///	-10^9 <= matrix[i][j] <= 10^9
+    ///	All the integers in each row are sorted in ascending order.
+    ///	All the integers in each column are sorted in ascending order.
+    ///	-10^9 <= target <= 10^9
+    pub fn search_matrix(matrix: Vec<Vec<i32>>, target: i32) -> bool {
+        if matrix.is_empty() {
+            return false;
+        }
+
+        let (m, n) = (matrix.len(), matrix[0].len());
+        let (mut x, mut y) = (0, n - 1);
+        while x < m && y < n {
+            let value = matrix[x][y];
+            match value.cmp(&target) {
+                Ordering::Equal => return true,
+                Ordering::Less => x = x + 1,
+                Ordering::Greater => y = y - 1,
+            }
+        }
+        return false;
+    }
 }