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学习资料
------------------------------http://community.topcoder.com/tc?module=Static&d1=tutorials&d2=binaryIndexedTrees
http://hi.baidu.com/wyl8899/item/c3ac1c0eec3516ea34990267
http://hi.baidu.com/solofancy/item/a6b7da6abdea54126995e65f
http://blog.csdn.net/pkqs90/article/details/10859155
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树状数组相对于线段树的优点
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代码短
常数低
易向高维推广
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