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Re:怎么递推?我当时想线段树觉得有问题,

Posted by wangfangbob at 2007-10-30 15:59:33
In Reply To:怎么递推?我当时想线段树觉得有问题, Posted by:ACM06060 at 2007-10-30 14:59:53
哦,比如一个区间[a,b]分成[a,c]和[c,b],那么[a,b]的4个关键域可以被[a,c]和[c,b]的关键域推出来:

比如[a,b]的最大和线段有3种情况:
1,在区间[a,c]里
2,在区间[c,b]里
3,横跨c点,横跨c点的最大和线段是从[a,c]区间的"以线段右端点为右端点的最大和线段的左端
点位置"这个点到[c,b]区间的"以线段左端点为左端点的最大和线段的右端点位置"这个点

然后这3个线段比一下和的大小就行了

其它的3个关键域也类似推出可以

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