# [PHP], <del>385</del> <del>335</del> <del>307</del> <del>270</del> 256 bytes

<!-- language-all: lang-php -->

    function c(&$m,$x,$r=-1,$d=0){if($r<0)$r=array_search(P,$m);$m[$r]=V;if(!in_array(T,$m))die;foreach([$r%$x?$r-1:-1,$m[$r-$x]?$r-$x:-1,$m[$r+$x]?$r+$x:-1,$r%$x<$x-1?$r+1:-1]as$o=>$n)if($n>=0&$m[$n]!=M&$m[$n]!=V){echo LUDR[$o];c($m,$x,$n,$o);}echo RDUL[$d];}

[Try it online!][TIO-jwc7je1k]

[PHP]: https://php.net/
[TIO-jwc7je1k]: https://tio.run/##rZBBa8IwFMfP66eI8DYTTLFlt8UobB4VRKqXEiTEuPbQpLw66BA/e9c4kV23eXgk/N7/F95LXdTdZFYXNbGIHndoa4/H0r3ThInu8OHMsfSOGPoEFYeWA8o45bCXCTuVBwo4SVjPNKL@3DVWoynoikPFBFQ5oJJb0ccGpdtdIjQLPbYvrTh4tLpP96lHaGeAcfoSng5aDK2aXY4bGn2j0RUFZwJtnAYWRKUb8HIKjoWx3FQmT8FzaiCXt9uWnawpPFls5uscvBKGXtdyHDwT50t3Pd8sctgrce6i8Zi86qY05E03NoIqJZLk0cNwNeRD8rvqLfIvK/uTtfxR2V0mzO6ylxKRoaT/UU7SZ8JE1H0B "PHP – Try It Online"

Uses a recursive depth-first search to crawl the map until all treasures are found.

Input is a one-dimensional array map and number of columns, example: `c( $map, 13 );`.
<br>Output is to `STDOUT` as `L,R,U and D`.

Or **242 bytes** to [output as numbers][1] (but I prefer the letters).



**Ungolfed**

    function c( &$m, $x, $r=-1, $d=0 ) {
    
        // locate starting room ($r) on first move
        if( $r < 0 )                        
            $r = array_search( 'P', $m );
    
        // mark square on map ($m) with V to show it has been visited
        $m[ $r ] = 'V';
    
        // end if no more treasures
        if ( ! in_array( 'T', $m ) )
            exit;
    
        // generate list of adjacent squares
        $dirs = [
            $r % $x ? $r - 1 : -1,            // Left
            $m[ $r - $x ] ? $r - $x : -1,     // Up
            $m[ $r + $x ] ? $r + $x : -1,     // Down
            $r % $x < $x - 1 ? $r + 1 : -1    // Right
        ];
    
        // consider valid directions for next move
        foreach ( $dirs as $o => $n )
            // if not a Wall or Mountain and not Visited
            if ( $n >= 0 and $m[ $n ] != 'M' and $m[ $n ] != 'V' ) {
                // display the direction
                echo 'LUDR'[ $o ];
                // and recursively keep crawling
                c( $m, $x, $n, $o );
            }
    
        // reached a dead end, go back to previous square
        echo 'RDUL'[ $d ];   // display the reverse direction
    
    }

[Basic Case][TIO-jwc7je1k]

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |P| | | | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | |T| | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | |M|M|M|T| | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | | | | | |T| | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

`DDDDDRUUUUURDDRUURDDRUURDDDLDLLLDRRRRURUUUURDDDDDLRRU`

[Locked Up][2]

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |P| | | | |M| | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | |M| | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | |T| | |M| | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M| | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | | | | | | | | | | | | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

`DDRUURDD`

[No Treasure:][3]

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|P|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

` `  &nbsp;*(no output)*

[No way to move][4]

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M|M|M|M|M|M|M|M|M|M|M|P|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

` `&nbsp; *(no output)*

[The world is a giant treasure][5]

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|T|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|T|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|P|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|T|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|T|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T|T|T|T|T|T|T|T|T|T|T|T|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

`LLLLLLUURDRURDRURDRURDDDLLLLLLLDDRURDRURDRURDRURUUUURDDDDDLRRUUUUURDDDDDRUUUUU`

[1x1][6]

    +-+
    |P|
    +-+

` `&nbsp; *(no output)*

[Back Alley][7]

`DDDDDRUUUUURDDDDDRUUUUURDDDDDRUUUUURDDDDDRUUUUURRRRRLLLLLDDRRRRRLLLLLDDRRRRR`

[Hedge Maze][8] (an original creation)

    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |P|M| |T|M| | | |M| |M|M|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    | |M| |M| | |M|T|M|T| | | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T| | |M| |M| |T|M|M|M| |M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M| | | |M| |M|M| | | |M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |T| | |M| |M| | | | |M| |M|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M|M| |T| | |M|M|M|M|M| |T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+

`DDRRUURLDDDDLLRRDRRUULRUURURRDDLDDRRRURRUULLUDRRRUDLDDDDR`


  [1]: https://tio.run/##rZBBa4MwFMfP81Ok8FYTGqmy22IqbOdCD9JLEQkxTg8m8uzAUfrZnelK2XVrD4@EX/6/x3vpm35Ks77piUF0WKLpHR5b@0FjJqb60@pj6yzRdAkdh5EDyijhUMmYndqaAqYxm5lCVF/lYBTqhu44dExAdwAs5F7MsUVry0uE5v6NVa0RtUOj5vSceoYxA4ySV9/aaxGMRXY5bmj1g1ZX5J0UxijxzIuFGsDJDVjmx7IbGS@9Z4uF3N5ue3YyunHghKbXfSwHx8T5gitxnoL1mrypodXkXQ0mgC4hkhyCp3AX8pD8rWaL3GXl/7K2vyp/yIT5Q/YqRKApmX@Uk@SFMBFM3w
  [2]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBT6gKfYkiZCWGRIU4cugaVvVvZ3YaWo/xY6TptIc9HET2fX13H5/jJGGy6HSTMAHKOeNDThPGZ1E81lq6tRjdx/4sYjH4Wh1NDZQZiNtN00CT/DewW/pjNNIQ77R0MUM4J/NhSgn3Q61voKluoakrnBH37FtLeB5E8TD30hw5rQcRtUaMUyIELuIfUdZFvGl@kqsLJW@izOvmfy9Dh89Dh8WQ1HRQ1jTlmBR6JEXMvkSxLjOLL@1WvS6FsXdg49fHW/2R@iGD3uD6xkXMs3ytqDAWixqI6dZT7nBzPei5KPCsp0Xt6AiuSBr58IWktIamJtjg1j40@g2jAfuZUMGbVE4pFVbMqSRDp5K6PEvA9TUQTA0w26BbNUm7x/w7GsAgEbCPt8DGpUrBpWDvVuEV0Lh0hu/TRAJ2jvpYRf2NwUwcxPSey85ur4H9tlLwFvu9R/ffon8ddnsF9gOZw4zBlH2XvE8K3ngHqTX2X/VifYX3icrbCSk8MD4JIEqBwDgi8Uxt99MCv1Oc9T2sclX/L8aqXrXEf6rivyL@HXyeTOhcsD4reWk6f3QE1zfS@xz3amKVr2vJ@kxlbWamgHwuIQvES5dz4bL0@EqDMQVMfsjOv1B2Ayu3Hd5wVyofD0XWeMNr21n/mVH01bp11dj41znlZbAtq5W5HbE2rLQSy9lxicFr5z@zvlhux@In
  [3]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBV6gKfUERshIDUUkcOXQNq/q3U5uG4rEAI02nPezhILLv67v7@BwnHsfzVjsex0A5Z3zAacz4NIhGWkO35sOHyJsGLAJPq6LQQKmBuF03DTRZ/Pp2Q38KhhrirYYuZgjnZDZIKOHeWOsaKNQtFPaFM@KufWcJz4MgGiy8NEdO635ArSHjlAhBH/HPKG0jXje/yNWFktdR6rYXf29Dh69Dh9mQ1LRQWjflmBS6JEHMvkSRLjOLLu1GtSqFkXtg49Xjnf5EvTGDTu/6to@Ya3laVmEkFjUQ063nhcPtda/TR75rPc8rR0dwRZLAg28koRUUmmBDv/Kp1q0ZNdjPhArepXIKqbBiTikZOqXU5VoCrqeBYGqA2QTdqkjaHebdUx96sYB9vAU2LlQKLgR7twqvgcaFM/yYJlrBPlZh3zCYiqOYPHDZ280c3O8rBm@x37t0/036h3EvYDfXYD@SGUwZhOyH5H2S8cY7SOXYf9WbdRXeJypvZ0zhkfGJD0ECBEYBiaZqu59m@J3stO9hpau6fzFW@aol/lMV/xXx7uHrZEJngvVZwWvT@aMjmN9IH3Pcy4lVvK4l6zOVtZmaAvK5hCwQL13OhcvS4zv1RxQw@Sk7/0LZDazcd3jDbal8PmRZ4w2vbSf/QyPrq7x11dj41znlZbAtq7W5HbE2rLQWy9lxicGq819ZXyy3Y/4C
  [4]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBT6gKfUERshJDokIcOXQNq/q3MxtC8ViAkabTHvZwENn39d19fI4TB/G81Y6DGCjnjA84jRmfhtFIa@jWfPgYedOQReBpVTQxUGogbtdNA40Xv77d0J/DoYZ4q6GLGcI5mQ0SSrgXaF0DTXQLTfrCGXHXvreE51EYDRZemiOndT@k1pBxSoSgj/hHlLYRr5uf5OpCyesodduLv9eh4@XQcTYkNS2U1k05JoUuSRCzr1Gky8yia7tRrUph5B7ZeP14rz9TL2DQ6d3e9RFzLU/LKozEogZiuvWycLi77XX6yHetl3nl5ARuSBJ68IUktIImJtjQr3yodWtGDQ4zoYI3qZxCKqyYU0qGTil1uZaA62kgmBpgNkG3KpJ2h3kP1IdeLGCf7oCNC5WCC8Her8IboHHhDN@nidawT1XY3xhMxVFMHrns7WYO7rcVg3fY7116@Cb9@7ibG7ifyAymDCbsuyR@lhHHe1jl2H/Vq3WXxBe8z1TeTkDhifGxD2ECBEYhiaZqw59n@J3svB9gpau6fzFW@aoV/nMV/w3xHuDzeExngvVFwYvT@aNDmN9I73Pgy4lVvK4V6wuVtZmaAvKlhCwQr1wuhcvK4yv1RxQw@SE7/0rZDazceHjLfal8QGRZ4y0vbif/UyPrq7x11dj41znlZbArq425PbG2rLQRy9lzjcG685esr1bbMf8J
  [5]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBT6gKfYkiZCUGokIcObQNq/q3MzsNxWUBRkqnPezhILLv67v7@BwnHsXzVjsexUA5Z7zPacz4NIyGWkO35oP7yJ@GLAJfq6KJgVIDcbtuGmic/QZ2Q38KBxrirYYuZgjnZNZPKOH@SOsaaKJbaOIKZ8Q9@9YSngdh1M@8NEdO60FIrQHjlAiBi/hnlLYRr5tf5OpCyeso9drZ3@vQ4cvQYT4kNS2U1k05JoUeSRCzL1Gky8yiS7tRrUph5B3YePl4qz9Rf8Sg07u@cRHzLF/LK4zEogZiuvWcOdxc9zouCjzreV45OoIrkoQ@fCMJraCJCTa4lU@1bs2owW4mVPAulVNKhRVz9pKhs5e6PEvA9TUQTA0wm6BbFUm7w/w7GkAvFrCPN8DGpUrBpWBvV@EV0Lh0hh/TREvYxyrsHwym4igm91z2drMA9/uKwRvs9y7dfZP@fdzNFdyPZAZTBhP2IImf5MTxFlYF9l/1at03xE9U4s6IwiPj4wDCBAgMQxJN1ZY/zTfAyU/8DrZ3Vfcvxtq/SmxAhv9UxX9F/Dv4Oh7TmWB9VvLqdP7oGBa30scc@f3EKl/XgvWZytpMTQH5XEIWiBcu58Jl4fGdBkMKmPyUnX@h7AZW7jy85sZUPiHyrPGaV7dT/LGR91XRumps/HZOeR1symplbkusNSutxHK2XGSw7PwX1heL7Zj/Ag
  [6]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBV6gKfUERshIDUUkcObQNq/q3MztNi0sDjJROe9jDQWTf13f@3DlOPI7nrXY8joFyzviA05jxaRCNtIZuzYd3kTcNWASeVkWhgVIDcbtuGmiS/fp2Q38MhhrirYYuZgjnZDZIKOHeWOsaKNQtFPaFM@KufWMJz70gGmRemiOndT@g1pBxSoSgj/hXlLYRr5vf5OpCyesoddvZ3@vQ/vPQfj4kNS2U1k05JoUuSRCzz1Gky8yic7tRrUph5O7ZePF4oz9Sb8yg07u87iPmWp6W7zASixqI6dZT5nB92ev0ke9aT/PKwQFckCTw4AdJaAWFJtjQr3ypdWtGDbYzoYIPqZxSKqyYs5MMnZ3sy7UEXE8DwdQAswm6VZG0O8y7pT70YgH7cA1sXGoruBTszSq8BBqXzvBzmmgB@1CFfcVgKo5icsdlbzcLcH9sM3iNve/S7Yv07@NuLuF@IDOYMgjZvSR@lBPHG1gV2H/Vq3XfED9SiTtjCg@MT3wIEiAwCkg0VVv@OC@Ak5/4LWznqu5fjLV71aIAx2oBLoh3C98nEzoTtE9KXp7OHx3E4mb6nEO/m1jl97WgfaLSNlNTYD6VmAVk4ZS5nAqXF4@f1B9RwOSX7P4zpR5YuffwiltT@YzI88YrXt9O8QdH3ltF66qx8ds55ZWwLquluQ2xVqy0FMvZcJnBovufWZ@9lGP@Gw
  [7]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBT6gKfYkiZCWGRCVx5KQtrOrfzmwaisv4MVI67WEPB5F9X9/5c@c4aZhOW@00TIFyznif05TxPEqGWkO3poP7xM8jloCvVVFsoLGBuF03DTSa/QZ2Q3@KBhrirYYuZgjnZNLPKOF@qHUNFOsWil3hjLhn31rC8yBK@jMvzZHTehBRa8A4JULgIv4ZjduI180vcnWh5HU09tqzv9ehw5ehw2JIalpoXDflmBR6JEPMvkSJLjNLLu1GtSqFiXdg48Xjrf5E/ZBBp3d94yLmWb5W7DARixqI6dbzzOHmutdxUeBZz9PK0RFckSzy4RvJaAXFJtjgVj7VujWjBruZUMG7VE4pFVbM2UuGzl725VkCrq@BYGqA2QTdqkjaHebf0QB6qYB9vAE2LrUVXAr2dhVeAo1LZ/gxTbSAfazC/sEgF0cxu@eyt5srcL9vM3iD/d6luxfp38fdXML9SCaQM4jZgyR@UhDHW1itsP@qV@u@IX6iEndCCo@MjwKIMiAwjEiSqy1/WhTAKU78DrZ3Vfcvxtq/alGAU7UAV8S/g6@jEZ0I2mclL0/njw7i6mb6mEO/n1jl9yVoz1ifqazNsSkgn0vIAvHc5Vy4zD2@02BIAZOfsvcvlGpg5dbDa@5M5SOiyBqveXk7qz83is5ata4aG7@dU14Im7JamtsSa81KS7GcLVcZLHr/hfXFvBzTXw
  [8]: https://tio.run/##7Zbfb9owEMefx19xlTxI1KCS0l9aSNG6PuwBT6gKfUERshJDopI4cugKq/q3MztLG5cFGCmd9rCHg8i@r@/8uXOcJEiWnW4SJEA5Z3zEacL4LIwnWku3luP72JuFLAZPq6PIQHMDcbtpGmia/fp2S38MxxrinZYuZgjnZDFKKeFeoPUNFOkWiobCGXHXvrWE50EYjzIvzZHTuh9Sa8w4JUIwRPwjmncRb5qf5OpCyZto7nazv5ehw19Dh/mQ1HTQvGnKMSl0SYqYfYliXWYWX9qtel0KY/fAxsXjrf5IvYBBb3B9M0TMtTwt32EsFjUQ062nzOHmetAbIt@1npa1oyO4ImnowReS0hqKTLBhWPvQ6DeMBuxmQgVvUjmVVFgxZy8ZOnvZl2sJuJ4GgqkBZht0qyZp95h3R30YJAL28QbYuNJWcCXY21V4BTSunOH7NFEB@1iF/Y3BTBzF9J7L3m6X4H7bZvAG@71Ldy/Sv4@7vYL7gSxgxiBi3yXxk5w43sKqxP6rXqz/iviJStwJKDwwPvUhTIHAJCTxTG3507wATn7id7C9q/p/Mdb@VUUBTtUCXBHvDj5Pp3QhaJ9VvDydPzqI5c30Pod@P7Gq76ugfabSNuemwHwuMQvIhdO5cHr2@Ur9CQVMfsj@v1AqgpWbD6@5N5UPiTxzvOYF7pR/cuTdVbauGhu/nlNeCpuyWpnbEmvNSiuxnC3XGRT9X8tYXzwXZPkT