In the set of n positive integers, find the largest element m, satisfy M=a + B, where a, a and a are the elements of the set S

Idea: first set sorting, time complexity Nlogn, and then the M from the maximum start to traverse, A and b respectively take less than m minimum and maximum, test whether the a+b is equal to M, if the small a right shift, if the big B shift left. The total time responsibility is n*n

int find (int s[], int n) {sort (s, S + N); for (int i = n-1; I >=2; i.) {int left = 0, right = I-1;while (left < righ T) {if (S[left] + s[right] = = S[i]) return S[i];else if (S[left] + s[right] > S[i])--right;else++left;}} return-1;}

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In the set of n positive integers, find the largest element m, satisfy M=a + B, where a, a and a are the elements of the set S