added problem 64

Author: SHA65536

problems/problem0064/min_path_sum.go

@@ -0,0 +1,35 @@
+package problem0064
+
+import "math"
+
+/*
+Given a m x n grid filled with non-negative numbers,
+find a path from top left to bottom right, which minimizes the sum of all numbers along its path.
+Note: You can only move either down or right at any point in time.
+*/
+
+func minPathSum(grid [][]int) int {
+	for i := len(grid) - 1; i >= 0; i-- {
+		for j := len(grid[0]) - 1; j >= 0; j-- {
+			if i == len(grid)-1 && j == len(grid[0])-1 {
+				continue
+			}
+			var r, d int = math.MaxInt, math.MaxInt
+			if i+1 < len(grid) {
+				r = grid[i+1][j]
+			}
+			if j+1 < len(grid[0]) {
+				d = grid[i][j+1]
+			}
+			grid[i][j] += min(r, d)
+		}
+	}
+	return grid[0][0]
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}

problems/problem0064/min_path_sum_test.go

@@ -0,0 +1,35 @@
+package problem0064
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type Result struct {
+	Input    [][]int
+	Expected int
+}
+
+var Results = []Result{
+	{[][]int{
+		{1, 3, 1},
+		{1, 5, 1},
+		{4, 2, 1},
+	}, 7},
+	{[][]int{
+		{1, 2, 3},
+		{4, 5, 6},
+	}, 12},
+}
+
+func TestMinPathSum(t *testing.T) {
+	assert := assert.New(t)
+
+	for _, res := range Results {
+		want := res.Expected
+		got := minPathSum(res.Input)
+		assert.Equal(want, got, fmt.Sprintf("%+v", res))
+	}
+}

readme.md

@@ -63,6 +63,7 @@ Each problem is in it's own directory, with test files. There are helper package
 | 0059 | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii) | [My Solution](./problems/problem0059) | ✅ |
 | 0062 | [Unique Paths](https://leetcode.com/problems/unique-paths) | [My Solution](./problems/problem0062) | ✅ |
 | 0063 | [Unique Paths II](https://leetcode.com/problems/unique-paths-ii) | [My Solution](./problems/problem0063) | ✅ |
+| 0064 | [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum) | [My Solution](./problems/problem0064) | ✅ |
 | 0066 | [Plus One](https://leetcode.com/problems/plus-one/) | [My Solution](./problems/problem0066) | ✅ |
 | 0067 | [Add Binary](https://leetcode.com/problems/add-binary) | [My Solution](./problems/problem0067) | ✅ |
 | 0069 | [Sqrt(x)](https://leetcode.com/problems/sqrtx) | [My Solution](./problems/problem0069) | ✅ |