题目7单选题
<img src="https://tihai-oss-cloud.itihey.com/img/1dac517aff62a020fcb3bbd85e78ab3f.png">级排列<img src="https://tihai-oss-cloud.itihey.com/img/f3d27b40325df5be74673968a46130af.png">的逆序数为 ( ),当<img src="https://tihai-oss-cloud.itihey.com/img/b90b31b1ea38b10fde41bb682e48a2f9.png">( )时,它是偶排列A. <img src="https://tihai-oss-cloud.itihey.com/img/241afd9013413a876a38dab4b1880511.png"> <img src="https://tihai-oss-cloud.itihey.com/img/642903beee01f33eb3756ecd8bceff87.png">或<img src="https://tihai-oss-cloud.itihey.com/img/dcdc5b5e9906b481d6a876c211dc9e31.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/241afd9013413a876a38dab4b1880511.png"> <img src="https://tihai-oss-cloud.itihey.com/img/dee0dd46a32a0df9d13efa1ab7cca7a4.png">或<img src="https://tihai-oss-cloud.itihey.com/img/b624cfb81151685f2630a28c791dfd60.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/162dda2f5284762577886dfffb0e23d9.png"> <img src="https://tihai-oss-cloud.itihey.com/img/a348b6f58e13e5c7c18c6482381df640.png">或<img src="https://tihai-oss-cloud.itihey.com/img/6e92483fe4231c72e29d5bac8869344d.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/162dda2f5284762577886dfffb0e23d9.png"> <img src="https://tihai-oss-cloud.itihey.com/img/642903beee01f33eb3756ecd8bceff87.png">或<img src="https://tihai-oss-cloud.itihey.com/img/b624cfb81151685f2630a28c791dfd60.png">