Two string - JavaScript - using object literal - creating a hashtable, and then, first string goes into as Hashtable - add it if not in; second string, add one on existing one.

Twostring10.cs

function processData(input) {
    var inp = input.split("\n"),
        i;
    for(i=1; i< parseInt(inp[0]) + 1; i++){
        
        console.log(hasCommonChar(inp[i*2-1], inp[i*2])? "YES":"NO");
    }
} 

function hasCommonChar(a, b){
    var i = a.length,
        map = {},
        c;
    while(i--){
        if(!map[a[i]]){
            map[a[i]] = 1;
        }
    }
    
    i = b.length;
    while(i--){
         if(map[b[i]]){
            map[b[i]]++;
        }
    }
   
    for(c in map){

        if(map[c] > 1){
            return true;
        }
    }
}

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});