Merge pull request #1 from ResponseTime/ResponseTime-branch

Create 0451-Sort-Characters-By-Frequency.go

Author: ResponseTime

Diff for: go/0451-Sort-Characters-By-Frequency.go

@@ -0,0 +1,29 @@
+func frequencySort(s string) string {
+    type charFreq struct {
+        c rune
+        f int
+    }
+
+    mp := map[rune]int{}
+    cs := []charFreq{}
+
+    for _, c := range s {
+        mp[c]++
+    }
+
+    for c, f := range mp {
+        cs = append(cs, charFreq{c,f})
+    }
+
+    sort.Slice(cs, func(i,j int) bool{
+        return cs[i].f > cs[j].f
+    })
+
+    ans := ""
+
+    for _, cf := range cs {
+        ans += strings.Repeat(string(cf.c), cf.f)
+    }
+
+    return ans
+}