练习题

一、一个游戏，前20关是每一

关自身的分数，
21-30关每一关是10分,
31-40关，每一关是20分,
41-49关，每一关是30分,
50关，是100分,
输入你现在闯到的关卡数，求你现在拥有的分数.

var guan = prompt("请输入你现在闯到的关卡数");
var fen = 0;
while(guan > 50){
    guan = prompt("请输入正确的的关卡数");
}
if (guan <= 20) {
    for(var gs = 0;gs <= guan; gs++){
    fen += gs;
    }alert(fen);
} else if(guan <= 30){
    for(var gs = 0;gs <= 20; gs++){
    fen += gs;
    }
    for(var gs = 21;gs <= guan; gs++){
        fen += 10;
    }
    alert(fen);
} else if(guan <= 40){
    for(var gs = 0;gs <= 20; gs++){
    fen += gs;
    }
    for(var gs = 21;gs <= 30; gs++){
        fen += 10;
    }
    for(var gs = 31;gs <= guan; gs++){
        fen += 20;
    }
    alert(fen);
} else if(guan < 50){
    for(var gs = 0;gs <= 20; gs++){
    fen += gs;
    }
    for(var gs = 21;gs <= 30; gs++){
        fen += 10;
    }
    for(var gs = 31;gs <= 40; gs++){
        fen += 20;
    }
    for(var gs = 41;gs <= guan; gs++){
        fen += 30;
    }
    alert(fen);
} else if(guan == 50){
    for(var gs = 0;gs <= 20; gs++){
    fen += gs;
    }
    for(var gs = 21;gs <= 30; gs++){
        fen += 10;
    }
    for(var gs = 31;gs <= 40; gs++){
        fen += 20;
    }
    for(var gs = 41;gs < 50; gs++){
        fen += 30;
    }
    fen += 100;
    alert(fen);
}

二、打印三角形

*
**
***
****

   *
  **
 ***
****

****
 ***
  **
   *


****
***
**
*


   *
  ***
 *****
*******

for(var h = 0;h < 4; h++){
    for(var a = 0;a <=h; a++){
        document.write("*");
    }
    document.write("<br />");
}
document.write("<br />");
for(var h = 0;h < 4; h++){
    for(var a = 3;a >h; a--){
        document.write("&ensp;");
    }
    for(var a = 0;a <=h; a++){
        document.write("*");
    }
    document.write("<br />");
}
document.write("<br />");
for(var h = 0;h < 4; h++){
    for(var a = 0;a <h; a++){
        document.write("&ensp;");
    }
    for(var a = 4;a >h; a--){
        document.write("*");
    }
    document.write("<br />");
}
document.write("<br />");
for(var h = 0;h < 4; h++){
    for(var a = 4;a >h; a--){
        document.write("*");
    }
    document.write("<br />");
}
document.write("<br />");
for(var h = 0; h < 4;h++){
    for(var a = 3;a > h;a--){
        document.write("&ensp;");
    }
    for(var a = -1;a < (h + 1 * h);a++){
        document.write("*");
    }
    document.write("<br />");
}