621 added

Author: aQua

Algorithms/0621.task-scheduler/README.md

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+# [621. Task Scheduler](https://leetcode.com/problems/task-scheduler/)
+
+## 题目
+Given a char array representing tasks CPU need to do. It contains capital letters A to Z where different letters represent different tasks.Tasks could be done without original order. Each task could be done in one interval. For each interval, CPU could finish one task or just be idle.
+
+However, there is a non-negative cooling interval `n` that means between two `same tasks`, there must be at least n intervals that CPU are doing different tasks or just be idle. 
+
+You need to return the `least` number of intervals the CPU will take to finish all the given tasks.
+
+Example 1:
+```
+Input: tasks = ['A','A','A','B','B','B'], n = 2
+Output: 8
+Explanation: A -> B -> idle -> A -> B -> idle -> A -> B.
+```
+
+Note:
+1. The number of tasks is in the range [1, 10000].
+1. The integer n is in the range [0, 100].
+
+## 解题思路
+
+见程序注释

Algorithms/0621.task-scheduler/task-scheduler.go

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+package Problem0621
+
+func leastInterval(tasks []byte, n int) int {
+
+	return 8
+}

Algorithms/0621.task-scheduler/task-scheduler_test.go

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+package Problem0621
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type question struct {
+	para
+	ans
+}
+
+// para 是参数
+type para struct {
+	tasks []byte
+	n     int
+}
+
+// ans 是答案
+type ans struct {
+	one int
+}
+
+func Test_Problem0621(t *testing.T) {
+	ast := assert.New(t)
+
+	qs := []question{
+
+		question{
+			para{
+				[]byte{'A', 'A', 'A', 'B', 'B', 'B'},
+				2,
+			},
+			ans{
+				8,
+			},
+		},
+
+		// 如需多个测试，可以复制上方元素。
+	}
+
+	for _, q := range qs {
+		a, p := q.ans, q.para
+		fmt.Printf("~~%v~~\n", p)
+
+		ast.Equal(a.one, leastInterval(p.tasks, p.n), "输入:%v", p)
+	}
+}