https://leetcode.cn/problems/kth-smallest-element-in-a-sorted-matrix/

Author: masx200

README.md

@@ -10,6 +10,8 @@ leetcode 测试
 
 ##### 包含的内容如下
 
+https://leetcode.cn/problems/kth-smallest-element-in-a-sorted-matrix/
+
 https://leetcode.cn/problems/find-k-pairs-with-smallest-sums
 
 https://leetcode.cn/problems/compare-version-numbers

kth-smallest-element-in-a-sorted-matrix/index.ts

@@ -0,0 +1,29 @@
+export default function kthSmallest(matrix: number[][], k: number): number {
+    const n = matrix.length;
+    let left = matrix[0][0];
+    let right = matrix[n - 1][n - 1];
+    while (left < right) {
+        const mid = left + ((right - left) >> 1);
+        if (check(matrix, mid, k, n)) {
+            right = mid;
+        } else {
+            left = mid + 1;
+        }
+    }
+    return left;
+}
+
+function check(matrix: number[][], mid: number, k: number, n: number) {
+    let i = n - 1;
+    let j = 0;
+    let num = 0;
+    while (i >= 0 && j < n) {
+        if (matrix[i][j] <= mid) {
+            num += i + 1;
+            j++;
+        } else {
+            i--;
+        }
+    }
+    return num >= k;
+}