From 2a1e4c065938ae5f3030cc529f065ff41880dc27 Mon Sep 17 00:00:00 2001
From: begeekmyfriend <begeekmyfriend@gmail.com>
Date: Mon, 11 Sep 2017 10:08:18 +0800
Subject: [PATCH] Search a 2D matrix

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
---
 074_search_a_2d_matrix/Makefile        |  2 +
 074_search_a_2d_matrix/matrix_search.c | 79 ++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 074_search_a_2d_matrix/Makefile
 create mode 100644 074_search_a_2d_matrix/matrix_search.c

diff --git a/074_search_a_2d_matrix/Makefile b/074_search_a_2d_matrix/Makefile
new file mode 100644
index 0000000..ea35465
--- /dev/null
+++ b/074_search_a_2d_matrix/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test matrix_search.c
diff --git a/074_search_a_2d_matrix/matrix_search.c b/074_search_a_2d_matrix/matrix_search.c
new file mode 100644
index 0000000..c759b0b
--- /dev/null
+++ b/074_search_a_2d_matrix/matrix_search.c
@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+static int binary_search(int *nums, int len, int target)
+{
+    int low = -1;
+    int high = len;
+    while (low + 1 < high) {
+        int mid = low + (high - low) / 2;
+        if (target > nums[mid]) {
+            low = mid;
+        } else {
+            high = mid;
+        }
+    }
+    if (high == len || nums[high] != target) {
+        return -high - 1;
+    } else {
+        return high;
+    }
+}
+
+static bool searchMatrix(int** matrix, int matrixRowSize, int matrixColSize, int target)
+{
+    if (matrixRowSize == 0 || matrixColSize == 0) {
+        return false;
+    }
+
+    if (target < matrix[0][0] || target > matrix[matrixRowSize - 1][matrixColSize - 1]) {
+        return false;
+    }
+
+    int row = 0;
+    int *nums = NULL;
+    if (matrixRowSize > 0) {
+        nums = malloc(matrixRowSize * sizeof(int));
+        for (row = 0; row < matrixRowSize; row++) {
+            nums[row] = matrix[row][0];
+        }
+        row = binary_search(nums, matrixRowSize, target);
+        if (row >= 0) {
+            return true;
+        } else {
+            row = -row - 1;
+            if (row == 0) {
+                return false;
+            } else {
+                row--;
+            }
+        }
+    }
+    int col = binary_search(matrix[row], matrixColSize, target);
+    return col >= 0;
+}
+
+int main(int argc, char **argv)
+{
+    int row = 3;
+    int col = 4;
+    int **mat = malloc(row * sizeof(int *));
+    mat[0] = malloc(col * sizeof(int));
+    mat[0][0] = 1;
+    mat[0][1] = 3;
+    mat[0][2] = 5;
+    mat[0][3] = 7;
+    mat[1] = malloc(col * sizeof(int));
+    mat[1][0] = 10;
+    mat[1][1] = 11;
+    mat[1][2] = 16;
+    mat[1][3] = 20;
+    mat[2] = malloc(col * sizeof(int));
+    mat[2][0] = 23;
+    mat[2][1] = 30;
+    mat[2][2] = 34;
+    mat[2][3] = 50;
+    printf("%s\n", searchMatrix(mat, row, col, atoi(argv[1])) ? "true" : "false");
+    return 0;
+}