simplified time string calculation

plugins/timer/timer.plugin.zsh

@@ -7,12 +7,8 @@ precmd() {
     local cmd_end_time=$(date '+%s')
     local tdiff=$((${cmd_end_time} - ${__timer_cmd_start_time}))
     unset __timer_cmd_start_time
-    local tdiffstr='/'
-    if (( tdiff >= 60 )); then
-      tdiffstr+="$((tdiff / 60))m"
-    fi
-    tdiffstr+="$((tdiff % 60))s"
-    local cols=$(($COLUMNS - ${#tdiffstr} - 1))
-    echo -e "\033[1A\033[${cols}C ${tdiffstr}"
+    local tdiffstr="$((tdiff / 60))m$((tdiff % 60))s"
+    local cols=$(($COLUMNS - ${#tdiffstr#0m} - 2))
+    echo -e "\033[1A\033[${cols}C \`${tdiffstr#0m}"
   fi
 }